INTRODUCTION 19 
findings are recorded upon a printed form from which, 
when the histological, bacteriological and parasitological 
studies have been completed, a set of cross index catalogue 
cards are typed; these are divided into the principal 
diagnoses and determinations. The report of the Zoo- 
logical Society, appearing at the end of their fiscal year, 
February 28th, contains a resume of the observations for 
the year, together with notes of interesting cases and 
experimental work. 
There have accumulated the records of nearly six 
thousand autopsies and upon them as a basis has been 
founded the following report of the incidence and nature 
of pathological manifestations in the various animal 
groups, using also as additional data, published reports 
from other gardens. The book might be described as a 
collection of our studies, parts of which have appeared 
as separate articles, but most of which are entirely new, 
put together with as much connection as the subject 
matter will permit. The zoological and pathological 
literature has been consulted very extensively, but 
except for the reports of zoological societies and 
the publications of special students, it usually rep- 
resents isolated notes by travellers and veterinarians 
so that many articles may have been overlooked. 
Therefore no claim of perfect completeness of reference 
is made, the statements resting chiefly upon our own 
records. The subject will be approached from the stand- 
point of description and incidence, but it is inevitable that 
comparisons and contrasts must be noted. 
Into the realm of evolution (1) I shall not venture 
because I appreciate a lack of adequate preparation for 
such an attempt, and because, even if such were not the 
case, the material at hand is lacking in data upon fishes, 
many kinds of reptiles and invertebrates. 
( 1 ) Those who are interested in the subject of disease in its effect on 
evolution are referred to Morley Roberts, Proceedings, Zoological Society, 
London, 1918, p. 247. 
