PROCEEDINGS—PERTHSHIRE SOCIETY OF NATURAL SCIENCE. dxxix 
in which the process had been carried out. In our own 
country, Professor Owen forms the connecting link between the 
Paris group just referred to and our modern Biologists. His work, 
like that of Cuvier, lay chiefly in the direction of comparative 
anatomy and classification. He, too, seemed to feel that the old 
conception of species was inadequate, but his strong prejudices 
prevented him from breaking down the old barriers. 
Our knowledge of animal life received two most important 
additions about the beginning of the reign, for it was in 1828 that 
Von Baer, a Russian Zoologist, first traced the animal embryo 
through all the stages of its development, thus founding the study of 
Embryology, which has since been carried to such wonderful per¬ 
fection by Huxley, Francis Balfour, Weissman, Geddes, and other 
recent Biologists. In 1839 the German Zoologist, Schwann, did for 
Zoology what Schleiden had already done for Botany, for he demon¬ 
strated that all animal tissues arise from single nucleated cells. 
A few years later, namely in 1846, Kolliker showed how these tissues 
arise by a process of cell division. In 1857 a further step in the 
same direction was made by Wolff, who showed that development 
from the germ consisted in a gradual building up of organs; and, 
lastly, in 1861 Max Schultz defined the cell as “a unit mass of 
nucleated living matter.” It will thus be seen, as Professor Geddes 
has pointed out, that the study of animal, as of plant life, has been 
one of gradually deepening analysis, namely, from organism to organ, 
from organ to tissue, from tissue to cell, and from cell to protoplasm. 
As regards purely systematic Zoology, our knowledge of the 
animal kingdom has been immensely enlarged within the last sixty 
years. It has been estimated that by 1837 some fifty thousand 
species of animals had been described, whereas, in 1897, the number 
exceeded one hundred and fifty thousand. If we turn to the 
literature of the subject we find that all the more important works 
have been published within this period. The first of the long and 
important series of British Museum Catalogues, for instance, was 
published in 1837. The proceedings of the Zoological Society were 
commenced in 1833, and those of the Entomological Society in 1836. 
Since then we have had the magnificent works of Gould, Yarrell, 
Bell, Owen, &c., as well as the publications of the Ray Society. 
Perhaps the most important results, however, are those which have 
accrued from the various exploring expeditions which have been sent 
out from time to time by our own and other Governments. Of these 
may be mentioned the classical voyage of the “ Beagle,” which 
afforded such a magnificent training for Charles Darwin, and the 
results of which were published in 1S39; the cruise of the 
“ Porcupine ” and the “ Lightning,” the reports of which were 
published in t 868, 1869, and 1870; and, the grandest of all, the 
voyage of the “Challenger,” which extended from 1872 to 1876. 
The reports of this last expedition were published in thirty-two 
quarto volumes, extending from 1880 to 1896, and include the 
researches of sixty of the most eminent Zoologists in all parts of 
the world over a period of fully twenty years. As one out of many 
memorable results of this voyage, eight thousand new species were 
