OBSERVATIONS ON THE LIFE HISTORY OF ASCARIS 
VITOLORUM, A PARASITE OF BOVINES IN THE 
PHILIPPINE ISLANDS 
PRELIMINARY PAPER 
By BENJAMIN SCHWARTZ 
Of the University of the Philippines, Los Batios 
ONE PLATE 
INTRODUCTION 
_ The occurrence of Ascaris vitolorum in cattle and water 
buffaloes in the Philippine Islands and the importance of the 
parasites as serious pathogenic agents have already been em- 
phasized by me.(3) Since the preparation of that paper, studies 
on the eggs and larve of these parasites have .led to certain 
conclusions concerning the effect of sunshine on the embryonated 
eggs and on the invasion by the larve of various organs that 
are of sufficient importance to warrant their publication at 
this time. Observations on the development of the eggs are 
also included. . 
DEVELOPMENT OF EGGS 
The eggs of Ascaris vitolorum vary considerably in shape 
and in size, as shown in Plate 1, figs. 1 to 10. Measurements 
of about seventy eggs showed a maximum length of 99 yp, a 
minimum length of 68 », a maximum width of 76 », and a 
minimum width of 65 ». Most of the eggs measured varied 
from 76 to 84 » in length and from 64 to 68 » in width. The 
majority of the eggs studied were more or less elliptical, although 
a small percentage of those that have come under my observation 
were almost spherical. 
Under the influence of climatic conditions prevailing in the 
Philippines in December, January, and February, during which 
time the approximate average temperature was about 25° C., 
the eggs, which are unsegmented when expelled from the host, 
segment rapidly, and within five or six days the outline of the 
embryo can be distinguished in cultures of eggs kept in Petri 
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