THE HAND AS AN UNRULY MEMBER. 415 
limited and superficial acquaintance with the habits and 
external appearance of the few known animals; how few 
these were, as compared with those we now know, may 
be seen from this, that, in 1748, Linnzeus enumerated two 
hundred and eighty different kinds of fish; at the present 
time, the Museum of Comparative Zoölogy at Cambridge, 
Mass., contains over nine thousand species of that class, 
about twenty-two hundred of which were collected in the 
late Thayer Expedition to Brazil. 
So impossible is it for any one person to gain a thor- 
ough knowledge of all animals, that we find men Sevging ; 
years, their lives almost, to the study of a single species ;* 
while it is daily becoming more and more apparent, that 
in order to advance or even to keep up in modern sci- 
ence, each must devote himself principally to a few 
branches of Natural History 
To show how far this division of labor has already ex- 
tended, take the single department of Comparative Anat- 
omy, which embraces the following lines of study: 1. 
The anatomy of a single species apúdasů by itself; 
as Anthropotomy, or kinai anatomy; Hippotomy, the 
anatomy of the horse, ete. When this kind of study is 
extended to the microscopic investigation of the struc- 
ture of tissues, it is called Histology. 2. One or more 
Species may be traced in their development and growth 
from their beginning as an egg to the adult condition, 
—this is Embryology. 3. We may enlarge our concep- 
tion of the plan of creation, by comparing with the ani- 
mals which now live the fossil remains of those which 
*For ee 2 dren pou descriptive mes of te text anda laze folio atlas atlas 
pre ete 845, compris quarto Hy ment sear 
3 t tr t igamen 
“ Traité ae) et Sea of only th he bones, de cong *darva of the yore or Cossus 
tigniperda), by Pierr A Fibs a quarto of 615 pages and eighteen 
