played by the results of Hermbstaedt's experiments
on the influence of different manures on the propor-
tion of gluten and starch in wheat. Wheat from
common soil, neither rich nor poor, has 9-20 per cent,
of gluten to 66-69 f starch ; manuring with human
urine yields gluten 39- 10 and starch 39*30, and each
in PHYSIOLOGICAL VARIATION 119
different manure more or less alters, between these
two extreme data, the proportions of these two im-
portant elements of the plant.
The foregoing instances afford an example of posi-
tive measurable variation in chemical constitution ;
and if we were better acquainted with the details
of the life-history of any species, we should readily
perceive the corresponding effects from the physio-
logical side : we should see, for instance, how such and
such chemical variation, which we can measure and
weigh, is of real advantage to those which possess it ;
while those without it suffer definite and generally
disadvantageous consequences.
In other cases we perceive the physiological effects,
while we are not yet acquainted with the degree or
even the nature of the variability. We all know that
different animals of the same or of different groups
react quite differently under similar unfavourable
circumstances. We know, for instance, that it takes a
much longer time to drown a frog than a reptile or a
bird, and we understand why ; we know also why a
duck or penguin can withstand submersion a longer
time than a hen or a quail. There are physiological
reasons for these facts, and we are familiar with them.
But in other cases such reasons must also exist,
although we cannot tell what they may be. For
instance, if different insects are subjected to the
120 EXPERIMENTAL EVOLUTION LECT.
same process which is injurious to life, as in Gratacap's
experiments, 1 considerable differences are easily
perceived, though not explained. While the common
fly withstands living in pure oxygen less than thirty
hours, Doryphora decemlmeata survives easily for
three whole days, and Colias phyllodoce cannot stand it
more than twelve hours. While the same DorypJiora
can live twenty-four or even forty-eight hours in pure
hydrogen, a species of Noctua cannot live more than
twenty minutes, nor Poinpilns unifasciatus more than
ten minutes. Why, we cannot tell, but there cer-
tainly is some physiological and chemical reason
accounting for the fact.
Every physiologist knows well that the same poison
exerts very different influences on different organisms.
For instance, while brucine acts on dog or frog in the
same manner as strychnine (although stronger doses
are required than of the latter) it acts very differently
on the common crab (Carcinus maenas}, which exhibits
no convulsions but only a peculiar movement of the
external mouth-parts. Picrotoxin, similarly, acts on
dog and frog like strychnine ; on the crab it induces
a powerful contraction which is most characteristic. 2
1 Gratacap, Vitality of Insects in Gases* American Naturalist, vol.
xvi., 1882, p. 1019.
2 Cf. Henry de Varigny, De t Action de la Strychnine, de la Brucine
et de la Picrotoxine sur le Carcinus maenas. Journal de V Anatomic et
de la Physiologic, 1889, Paris. Also : H. de Varigny and Paul Langlois,
in CHEMICAL VARIATION
It may be argued that such instances are not very
convincing : they concern very different species and
genera ; how can it be proved that such important
variations occur within the same species, for there is
the point ? To this the answer is easy to give, and
if we turn to any given species, we cannot fail to
notice important differences. Take the human species,
for instance, and consider the differences between man
and woman, then those between the races of man,
and finally between the different men of the same
race.
As an instance of chemical difference between man
and woman, here are the percentages of the principal
components of bony structures in man and woman of
the same age, after Milne-Edwards :
Woman. Man.
Phosphate of Lime 62*15 5&'3~
Carbonate -. 4-52 9-98
Organic Substances 33'33 3170
Inorganic 66*67 68*30
And it must be noticed that the differences vary
according to the age of the patients, and even to the
side of the body. While in the young the proportion of
inorganic substances is smaller than in the adult, the
bones of the right side of the body contain more
Sur r Action de quelques Poisons de la Serie cinchonique sur le Cardnus
maenas (ibid. 1891), where similar facts are recorded.
EXPERIMENTAL EVOLUTION LECT.
than those of the left side, as H. Milne-Edwards
clearly recognized in his investigation on animals, and
such differences certainly obtain in man, as direct
experiments have shown. And such differences are
to be met not only between man and woman, between
one side and another, but also between one part and
another, lime-salts being more abundant in the thigh-
bone than in the arm, &c.
If we turn to the chemistry of the blood, the same
facts appear. Quetelet has analyzed the salts which are
contained in this fluid, and has seen that the differ-
ences arc as follows :
Man. Woman
At one year 14/2 13-3
At ten years 37-1 34-4
At thirty years 98*9 78-4
There is more iron in male than in female blood
(Boussingault) ; there arc also more salts in male than
in female, more in the right thigh of the duck than in
the left one ; there are more red blood-corpuscles in
man than in woman (142 against 127, after Becquerel
and Rodier, or 4*5 against 3*5, after Malassez), and
so on ; and all these minute or important differences
in anatomical or chemical structure are accompanied by
more or less important variations in physiology. Of
these differences I shall give only one instance : it
is admitted in forensic medicine that when man and
in ARGUMENTS FROM PATHOLOGY 123
wife are drowned together, the wife is considered as
having died the last, because it is known that woman
faints sooner, and has therefore more chances to survive
than man, as experience has shown.
So much then for variability between the different
sexes of the same species. If we now compare two races
of the same species mankind again similar differ-
ences come in. 1
While man and woman are respectively more liable
to certain diseases, each race seems to offer different
predispositions to the principal diseases flesh is heir
to. Pathologists are well acquainted with this fact,
and numerous instances of it are known. The following
figures show the death-rate from marsh fever among
Europeans (Englishmen) compared with negroes, in
different countries : 2
Death-rate per 1,000
Englishmen Negroes.
Jamaica 101-9 8-3
Guiana 59'2 8'5
Trinidad 6r6 3'2
Sierra Leone 410^0 24
It has been sometimes said that negroes are entirely
refractory to malarial fever : the fact is not accurate,
but the figures show, at least, that the black race has,
1 Cf. G. Delaunay's interesting Etudes de Biologic Comparce basees sur
V Evolution et la Nutrition. 1878-9. A. Delahaye, Paris.
- After Borclier, Geographic Medicate. Paris, 1884, p. 475.
124 EXPERIMENTAL EVOLUTION LECT.
for some reason or other, much less to fear from malaria
than the " white devils." The same difference is found
concerning tuberculosis : while it is more dangerous
for Polynesians and negroes than for whites, it is more
deadly for the whites than for the Mongolians, among
whom it has been said that Thibetans quite escape
the disease. The statement may have been exagge-
rated : at all events, it shows that the yellow race enjoys
comparative immunity from tuberculosis. Similar
instances are frequent among animals : not only do we
meet with instances of diseases which are peculiar to
some species only, 1 but within the same species some
breeds enjoy immunity while others do not. For in-
stance, Prof. Chauveau has shown that the sheep 01
Algeria enjoy a much greater immunity in respect to
anthrax than those of France, and the same differ-
ence obtains among asses. This is a racial character,
for foreign breeds living in Algeria do not acquire it ;
but the Algerian breeds transferred into Europe seem
1 For instance, anthrax affects sheep especially, while it is scarcer
among oxen, hogs, and horses, and is never met with among birds. To
glanders the pigeon seems to be the only bird at all susceptible.
Syphilis is peculiar to man, though it possibly may be seen in apes
and hogs. Rats and mice enjoy an almost perfect immunity from
diphtheria, and any number of similar cases may be found in any text-
book on Bacteriology. Perfect immunity is rather doubtful, but it is
quite certain that many virulent diseases, due to microbes, exist spon-
taneously only in a limited number of species, but may be conferred
experimentally upon some or many others under experimental condi-
tions.
in IDIOSYNCRASY 125
to lose it gradually, so that the influence of environ-
ment appears to have something to do with it.
And now, if we consider men of the same race
and the same facts would appear if we were to con-
sider individuals of any species of animals or plants
are we not all acquainted with facts of very notable
variability ? The same external influence acts quite
differently upon them, and of four men standing in a
draught, for instance, one will have pneumonia, the
other rheumatism, number three a bad cold, and
number four nothing at all but a temporary relief
from the heat of the day.
The very same morbid influence typhoid fever as an
instance acts differently, producing in the one patient
gastric symptoms, while cerebral trouble is predomi-
nant in another. Every physician can furnish any
number of similar instances, and can also show that
while in every epidemic of every disease there are
different forms of the same disease which are doubt-
less in correspondence with different personal variabi-
lities or idiosyncrasies, these idiosyncrasies vary from
one time to another, so that in one epidemic one form
predominates, while in another some different form
is most frequent. It thus seems that personal varia-
tion varies according to seasons and periods under
unknown influences. Or else, if no variation is
assumed to exist in the patients, there then exists
EXPERIMENTAL EVOLUTION LECT.
some variation in the pathogenetic organism. For
the present purpose this comes to exactly the same
thing, our only point being to show that variability
does exist in a marked manner.
Later on I shall have something to say concerning
the degree of variability among pathogenetic organ-
isms under different modes of culture or treatment ; it
is enough here to allude to the general fact of the
attenuation of many sorts of virus which has led to
the humane although as yet unexplained l practice of
vaccination ; but something must now be said concern-
ing the external manifestation of this variability.
Many bacteriologists have thought at times that it
might be possible to transmute one micro-organism
into another under definite circumstances, and we have
all heard of Biichner's or other experiments concerning
the relationship between the common hay bacillus and
the typhoid fever bacillus, as well as of similar in-
vestigations. But investigators seem to think much
too highly of mere morphological transmutations, and
to have too much disregard for other transmutations
which are in fact of much greater importance. They
seem to be running after shadows while substantial
reality lies disregarded at their very feet. Let us take
1 " Unexplained " refers of course to the process by which a bacillus
or bacterium, although in appearance unchanged, becomes incapacitated
for the production of disease of a virulent type.
in CHAUVEAU'S EXPERIMENTS 127
an instance. Here is that much investigated anthrax
bacillus. Many bacteriologists have tried to determine
morphological variations of the species through various
experimental methods, hoping to see it assume quite
different characters : but they have utterly failed.
Professor Chauveau studying the same general topic
of variability, has investigated it not on the morpho-
logical side, but on the physiological one. And he
asks very appropriately whether a bacillus which has
entirely lost its virulence, while retaining its morpho-
logical appearance which is always very simple
has not varied more than a bacillus in which form
might have varied while the pathogenetic properties
had remained unaltered ? The answer seems to me
manifest, that variability of virulence is of greater
importance than that of form and external appear-
ance, especially in the case of such very simple and
undifferentiated organisms, since this testifies to
deep modifications in the chemistry and vital pror
perties of the organism. How much more would
this be evident if the new characters acquired by
the organism were to remain unaltered from one
generation to another, without it being necessary
to provide permanently the special conditions or
the peculiar environment which initiated the produc-
tion of new characters ? And this case is not of
hypothetical nature ; it really exists, and I have been
128 EXPERIMENTAL EVOLUTION LECT.
a daily witness to it. Professor Chauveau, from long,
and, as usual very careful experiments on Bacillus
anthracis, has been able to show that while no known
method can as yet, entirely destroy the pathogenetic
influence of this micro-organism, nor confer upon it
new and different properties, the pathogenetic influence
may be destroyed to the extent that it can no longer
harm the animals in which it makes itself the most
easily felt. Such virus may be inoculated into guinea-
pigs and mice without doing the slightest harm. But
it has not entirely lost its properties, since it retains
its vaccinal influence : while apparently no longer
noxious to animals, while producing no disease nor
pathological symptoms, it acts like a vaccine lymph,
and confers immunity against the inoculation of viru-
lent bacillus, as experiment shows. Again, these devi-
talised or altered bacilli, which only retain a vaccinal
influence, may be made to acquire virulence of the
highest type through very simple experimental pro-
cesses. Lastly, these attenuated bacilli retain their
new characters (of non-virulence and of mere vaccinal
aptitude) as long as is required, without it being
necessary to use particular methods of any sort, and,
as M. Chauveau remarks, if one were to consider
these bacilli in themselves, apart from their origin,
and without knowing what they may be made to
become under appropriate experiments, they might
in CHAUVEAU'S EXPERIMENTS 129
certainly be looked upon as a distinct species. Between
this ultra-attenuated and the highly virulent breed
many intermediate types exist, but they have less
fixity, and their nature as measured through their
pathological effects is less constant. At all events
Professor Chauveau has succeeded in obtaining three
types of Bacillus anthracis :
Firstly, the ultra-attenuated type, which has lost all
pathological properties, and produces no disease even
in the most delicate and appropriate animals (mouse,
guinea-pig), but retains vaccinal influence, and can be
used for vaccination of the same animals against the
disease ;
Secondly, the semi-attenuated type, 1 which kills
some species of animals (rabbit and guinea-pig), but
acts only as a vaccine in other larger animals ;
Thirdly, the less attenuated type, which kills the
rabbit, guinea-pig, and sheep, and plays the part of a
vaccine only with the horse or oxen.
These different types may exist in Nature, and some
facts go to show that some of them probably do
exist.
The foregoing facts are of undeniable importance
in regard to the question of physiological variability,
1 This type may be obtained either by attenuation of the highly
virulent type, or by partial revivification of the attenuated bacilli. The
latter method is certainly preferable.
130 EXPERIMENTAL EVOLUTION LECT.
as they clearly show that while no difference at all
can be discovered in the external appearance of the
different types, considerable variation is present when
physiological properties are taken notice of.
I have quoted this case at some length, because it is
one of the most satisfactory yet obtained ; but similar
instances are very numerous in bacteriology, where we
perceive that very considerable differences of a phy-
siological nature may exist although not perceptible
from the morphological standpoint. 1
Zoology also provides us with other facts which are
of great interest. I refer to those which concern the
considerable physiological difference which obtains
between two closely related species, the brown and
the green frog (Rana esculenta and temporarid), when
subjected to identical experiment.
In 1 88 1 Monnier 2 noticed that brucin and its
different compounds act differently on these two
species. In R. esculenta this alkaloid determines a
paralysis of the motor nerves, and at the same time
an increase in the excitability of the spinal cord. Of
1 Cf. A. Chauveau : Sur les Proprietes vaccinates de Microbes ci-devant
fiathogenes transformes en Microbes d'apparence saprogene. Archives de
Medecine Exptrimentale, March, 1889, p. 161. Also, by the same
author : Recherches sur le Transformisme en Microbiologie pathogene.
Des Limites, des Conditions ct des Consequences de la Variabilitc du
Bacillus Anthracis. Ibid. November, 1889, p. 757.
2 Archives des Sciences Physiques et Naturelles, Geneva, 1881.
in GREEN AND BROWN FROG 131
course, the influence on motor nerves prevents the
spinal influence from being detected, unless the experi-
ment is performed in a particular manner. In jR.
temporaries the symptoms are quite different ; tetanic
convulsions appear, and if the dose is considerable,
motor paralysis ensues later. The case is the same
with the common toad.
Similar facts had been witnessed years before by
many physiologists. As early as 1864 my much re-
gretted master Vulpian : found that the same poisons
operate differently on the circulatory system of the
two species. Two years afterwards J. L. Prevost 2 wit-
nessed facts confirmatory of the preceding, concerning
the same animals when subjected to the influence of
veratrin ; the heart being arrested in one case, while
it is merely slackened in the other. Then Schmie-
deberg, in i8/4, 3 took up the question, studying the
influence of caffein, and saw that in R. temporaria
caffein operates in determining a local action which
gradually spreads a sort of muscular rigor, accom-
panied by a decrease in excitability ; in R. esculenta
1 Sur les Differences entre les Grenouilles rousses et les Grenouilles
vertes sous le Rapport des Effets produits par les Substances Toxiques et
sptcialement par les Poisons du cceur. Bull. Soc. Philomatique, 1864,
p. 94.
2 J. L. Prevost, Recherches Experimentales relatives a F Action de
la Veratrine. Thesis, Paris, 1886.
3 Ueber die Verschiedenheit der Caffeinwirkung an Rana temporaria
und R. esculenta. Arch. f. Exp. Path, und Pharm. 1874.
K 2
132 EXPERIMENTAL EVOLUTION LECT.
there appear, on the contrary, an increase in excita-
bility and tetanic convulsions. But after two or three
days the symptoms become similar in both species.
Pilocarpin, also, acts differently on the two above-
mentioned species, as Harnack and Meyer have
shown. 1 In Rana temporaries, pilocarpin induces
paralysis ; in R. esculenta, tetanus. Nicotin induces
convulsions, followed by paralysis, in esculenta,
while- paralysis is the immediate result in temporaria.
Similarly, pyridin induces tetanus in esculenta,
and in temporaria the symptoms resemble those of
picrotoxin poisoning. L. Wintzenried has con-
firmed Monnier's results on the different influences
of brucin, 2 and Vulpian, 3 in a later paper,, investi-
gated the accuracy of the statements of both to his
complete satisfaction. Lastly I may be allowed to
quote a few lines from a paper by Messrs. Lauder
Brunton and Cash, 4 which bears very exactly on the
topic : " Johannsen [who was working under Schmie-
deberg's direction] observed in the frogs with which he
1 Harnack and Meyer, Untersuchungen it. d. Wirkungen des fabor-
andialkaloide, nebst Bemerkungen u. d. Gruppe des Nicotins. Arch. /.
Exp. Path, und Pharm.
2 Recherches Experimentales relatives a V Action Physiologiqite de la
Rrucine. Thesis, Geneva, 1882.
3 Lemons sur V Action Physiologique des Substances Toxiques et Medica-
menteuses. 1882.
4 Lauder Brunton and J. Th. Cash, On the Circumstances which
modify the Action of Caffeine and Theine upon Voluntary Muscle.
Journal of Physiology, vol. ix. p. 112, 1888
in GREEN AND BROWN FROG 133
experimented that the muscles became rigid at the
place where caffein was injected, and this rigidity
gradually extended to the rest of the body, but he
failed to observe any tetanus. About three years
afterwards, Aubert arrived at results entirely opposed
to those of Johannsen, rinding that caffein in the
frogs with which he experimented produced marked
tetanus, but very slight rigor. These contradictory
results induced Schmiedeberg again to take up the
subject, and he found that the discrepancy be-
tween the statements of Johannsen and Aubert was,
to a great extent, due to the kind of frog employed
by each observer in his experiments, the former having
used specimens of R. temporaria, and Aubert of
R. esculenta. According to Schmiedeberg, in R. tern-
poraria caffein produces muscular rigor, without
tetanus, the rigor beginning at the place where the
poison is applied, and extending over the body so
gradually that the muscles first attacked may be
completely contracted and rigid, while others may be
still slightly irritable. On the other hand, in R.
esculenta, caffein frequently produces a violent and
continuous reflex tetanus, without any rigidity of
muscle other than that dependent on the tetanic con-
traction. It is only at a late stage of the poisoning,
two or three days after the caffein has been given, that
these differences between these two kinds of frogs
134 EXPERIMENTAL EVOLUTION LECT.
become equalised, increased reflex action and even
tetanic convulsions occurring in R. temporaria, and
distinct stiffness of the muscles becoming observable
in R. esculenta, although this stiffness never becomes
so great as in R. temporaria"
The foregoing differences in the nervous system of
these two very closely related species are again exem-
plified in other experiments, for Lautenbach 1 has shown
that while the nerves of Rana temporaria are never
excited by heat lower than 49 centigrade, those of
R. esculenta are excited as soon as the temperature
attains or exceeds 20 centigrade ; and, on the other
hand, a friend of mine, M. C. Contejean, a dis-
tinguished young physiologist, informs me that,
according to his own experiments, considerable dif-
ferences are noticeable in individuals of the same
species which differ in colour. While frogs whose
skin contains numerous pigment granules withstand
for some time the effects of having part of their blood
replaced by salt solution, frogs whose skin is sparsely
coloured resist during a much shorter period. Again,
the same physiologist informs me that while Rana
esculenta and temporaria possess digestive glands in
the lining of their cesophagus, the toad has none.
Also, while the green and brown frog are provided
1 The Physiological Action of Heat. Journal of Physiology, vol. ii.
in GREEN AND BROWN FROG 135
with gastric glands which are exactly similar, the
brown certainly produces a much larger amount of
pepsin. These are differences which may be of great
importance in the life of the animals or may go
with others yet unknown to make considerable differ-
ences yet nothing in the external character of the
animals would lead us to suppose that they were
present.
Among the facts which illustrate this physiological
variability I shall quote a few more. We all are
acquainted with the fact that while many varieties of
grape-vine are killed by some fungus or insect Phyl-
loxera, for instance others do not suffer at all, or
at least, as a rule, withstand the unfavourable effects.
We know also that while the venom of a snake is
deadly for most other snakes, it is not so for the same
species, as Surgeon Waddell x has recently shown with
great care ; we have all heard of cases when the same
plant is toxic for some animals and is not so for
others. Willoughby in his Ornithologia 2 says that the
common quail eats hellebore and water-dropwort
(Cicuta] without danger ; Daniel Duncan 3 says the