188 
POPULAR SCIENCE NEWS. 
[December, 1890. 
is afforded bj comparison of other parts, as, for 
instance, the brain, in regard to its division into 
lobes. Nothing could be more interesting than a 
comparative study of the brains of five tjpical 
animals, such as we have named. It would be seen 
^that in all there are the same number of paired 
lobes and having the same serial arrangement. But 
the relative size of these lobes varies as we go 
successively from the lowest group, fishes, to the 
highest group, mammals. That lobe which is the 
seat of ihe higher functions of mentality, namely, 
the cerebrum, is small in fishes, but, as we pass 
to the higher groups, it becomes larger and larger, 
until in the mammal-brain it overtops the others, 
constituting three-fourths of the brain-mass. 
These comparisons inevitably suggest the question 
of the genetical relationship of the five classes 
of vertebrates. Is there a true family relationship 
among them .' Are they all descended from a 
common ancestral vertebrate type.^ The interested 
reader can only be referred to the literature upon 
this subject. However, in concluding this paper, 
we may refer to two or three points that have a 
bearing upon this great quostion, and that are 
illustrative of the great mass of evidence that, to 
almost all persons who have studied the matter, 
is convincing of the truth of the doctrine of evolu- 
tion. 
1. It may have occurred to the reader that while 
what is said above is true of the five animals under 
examination, there are some vertebrates that do not 
have four pairs of limbs; some fishes — for instance, 
the common eel — that have only one pair of fins, 
and some reptiles — as the snakes — that have no 
limbs at all. Now if all vertebrates descended from 
an ancestral generalized type, those now living 
which lack two pairs of limbs must have lost these 
parts in the process of evolution. Also it is antece- 
dently probable that in some the parts would not 
yet be fully lost, but in process of gradual disappear- 
* ance. That this is the fact is most strongly indi- 
cated by the presence of imperfect (called rudi- 
mentary) limbs, or arches for the support of limbs, 
in some of the fishes and snakes. Thus in the boa 
constrictors there is a pair of claws, supported by 
bones, the positions and attachments of which are 
the same as of the hinder limbs of other reptiles, as 
the lizards. And while some fishes when full-grown 
lack any trace of ventral fins, they all pass through a 
stage of embryonic development in, which two jx^iirs 
of limbs are present. 
2. There is a single animal, the lancelet, which, 
while thrown with the fishes in classification, is 
much lower in rank — is the lowest type of organiza- 
tion among the vertebrates. In the lancelet there is 
no bony vertebral column or skull, but in their place 
a gelatinous cord, called the notochord. Overlying 
this cord is a nerve-axis, but its anterior part is not 
developed into a brain. The blood contains only 
colorless corpuscles, whereas that of all other verte- 
brates contains both white and red corpuscles. Now 
all other vertebrate animals — every species of fish, 
amphibian, reptile, bird, and mammal — pass through 
a stage of embryonic development in which they are 
like the lancelet in the characters just named. The 
inference is, that all vertebrates have been derived 
from an ancestral form which resemblgd the now 
living lancelet in respect to these fundamental 
features. 
3. The study of fossils shows that in past ages 
of the earth there lived vertebrates which were con- 
necting types between the clas es now living. Thus 
some were partly fish-like and partly reptilian ; 
others, partly reptilian and partly bird-like, etc. 
Also fossils are known which form a tolerably com- 
plete series of types between these generalized 
forms and the classes of vertebrates now living. 
Moreover, the strata in which they are found prove 
that the succession of types in time was from the 
generalized forms to those of living animals. 
Union College, Schenectady, N. Y. 
[Special Correspondence of Popular Science New8.\ 
PARIS LETTER. 
Swallows are leaving and scientists are coming 
back. The vacations are over, and after a trip to 
the sea-shore or to the mountains, all return to their 
business, and the scientific establishments re-open 
their doors; lectures and courses are again in full 
play. The season of work has begun — of indoor 
work, as nature is now going to sleep. Although it 
is rather late now to communicate the information, 
as far as immediate application is concerned, here 
are some observations made by some Swiss shep- 
herds of the Zurich canton, concerning the prognos- 
tication of weather through the observation of 
plants and insects. When Alsine media opens its 
corolla by 9 A. M. and keeps it open till 4 P. M., 
approximately, the weather will be fair the next day ; 
but if the flower is not open at 9 it predicts rain. 
If the flowers of Galium rerum give off a strong 
smell, rain is not far off. When the "petals of Oarlina 
vulgaris shut, rain is coming. Flowers of Calen- 
dula pluvialis remain closed after 7 A. M. when rain 
is to pour the same day. If leaves of Oxalis aceto- 
sella shut, rain, or cold, or a storm are near. Lap- 
sana communis must not keep its flower open at 
night; when it does it means rain. Such is also 
the case if Draba verua inclines its leaves toward 
the ground, and if Crataegus latifolia turns the 
superior aspect of its leaves in the same direction. 
The Zurich shepherds consider these various plants 
as so many barometers, and it is quite certain that 
many flowers and leaves do exhibit definite peculiar- 
ities when some change of the weather is impend- 
ing, but we would not advise to dispense totally 
with the usual barometer. Marshal Bugeaud, in 
his African campaign, had with him a glass jar 
containing some green frogs (thyta arhorea) for the 
purpose of ascertaining the future of the weather; 
these animals indicated it by climbing, or by going 
down, on the side of the glass, and the Marshal said 
they were capital barometers. With many others, I 
tried the plan, and never saw that they cared at all 
about the weather, and their movements indicated 
nothing at all, as they always kept as high as possi- 
ble, whatever the weather might be. 
Bacteriological studies are being pursued in many 
directions, and with success in France and Ger- 
many, where a great number of men have trained 
themselves in the special work and methods of this 
recent science. Two periodical publications are. in 
France, especially open to bacteriological re- 
searches ; the one is the Archives de Pathologie Ex- 
perimentale, edited by Professor Strauss, of the 
Medical School ; theother is the Aniialesde I'lnstitute 
Pasteur, conducted by Professor Duclaux, a very 
able and talented scientist, a member of the Acad- 
emy of Sciences, and one of the most remarkable 
men in the art of grasping the delicate points of a 
subject at first glance, and of explaining them en 
ahrupto in the most clear and precise language. 
He possesses the French genius in the highest 
degree, and it is a pleasure to listen to him when 
explaining a difficulty or criticising a theory. His 
Annales are full of excellent information, inasmuch 
as he has assumed himself the task of reviewing the 
more important foreign publications. 
Among the principal papers iecently published, 
I would call the attention on Gabritchevsky's re- 
searches on Chimiotaxis. This new name has 
been set forward by PfelTer, and expresses the fact 
that the micro-organisms endowed with mobility 
are attracted or repelled by definite chemicals, or- 
ganic or inorganic. This fact has given birth to a 
new method of research. If we want to know 
whether such or such microbes are present in such 
and such water, or matter, we prepare some 
capillary tubes filled with any substance which at- 
tracts the micro-organisms ; one end is shut and 
the other dips in the water or matter to be exam- 
ined. In a short time the micro-organisms get in 
the capillary tube, when they are easily detected 
by the ordinary methods. This new method is a 
very curious one, and no doubt will be extensively 
used, as it will render bacteriological analysis much 
more rapid and easier. 
Another very important paper is by Winogradsky. 
and refers to the agencies of nitrification. Scien- 
tists have long been perplexed by the question of 
ascertaining how, and under what form atmospheric 
nitrogen can be introduced in plants, and help to 
build their chemical structure. As all the nitrogen 
in animals is given to them by plants, the question 
is of great biological interest. It is known now 
that nitrogen gets into plants principally, if not ex- 
clusively through the agency of some micro-or- 
ganisms which dwells in the roots of plants, and 
when these micro organisms are killed by heat, 
for instance, the plant suffers and dies, unless some 
of them are artificially introduced in the roots. 
These micro-organisms — or this one, as one only 
has been discovered yet — are always present in the 
soil and their influence on life generally considered 
is one of utmost importance. 
M. Drake del Castillo, an able French botanist, 
has recently obtained a reward from the Frencli 
Academy of Sciences for a good memoir which he 
has published on the Polynesian flora. The Acad- 
emy had proposed a question, asking the significance 
of the flora of Polynesia generally. M. Drake del 
Castillo, the successful competitor, after a careful 
study of the matter, comes to the conclusion that 
the whole flora is of foreign origin. The idea of a 
former Polynesian continent, of which the present 
islands and archipelagos should be vestiges, — the 
highest parts, — must be discarded, for geological 
and floral reasons. Sea soundings exhibit enor- 
mous depths between many islands or groups, and 
it seems impossible that the former continent could 
have been so deeply immersed. Then the character 
of the flora shows that all the species of Polynesia 
are either cosmopolitan or of American and Asiatic 
origin. The flora ha^i been introduced ty currents 
and other natural agencies of dispersio 1. But a 
curious fact is that Polynesian flora exhibits peculiar 
features, and M. Drake del Castillo is of t le opinion 
that the migration took place a long tim? ago, and 
that while the originil species have generally dis- 
appeared and died out in their primitive habitat, to 
be replaced by analogous but different forms, the 
plants which migrated to Polynesia have kept their 
original forms. Pol\nesia would then present an 
older flora than is commonly believed. Another 
hypothesis is, that while the Asiatic and American 
species did persist, the species introduce 1 in Poly- 
nesia varied somewhat, on he contrary, on account 
of the climate and nevv surroundings. Both expla- 
nations are likely enough. At all events, the prin- 
cipal cpnclusion is that no Polynesian continent has 
existed, and that the flora of Polynesia is an intro- 
duced one. Although short, M. Drake del Castillo's 
memoir is full of good information, well sum- 
marized. 
Books are scarce at present; during tlie summer 
months publishers do not issue many, but now 
comes the season for new publications. However, 
we must signalize M. Armand Colin's new series — 
an Encyclopedic Horticole et Agricole, a series i>l 
