THE DEVELOPMENT OF THE EGGS OF ASCARIS 
LUMBRICOIDES * 
By LAWRENCE D. WHARTON 
(From the Zodlogical Laboratory, College of Liberal Arts, 
University of the Philippines) 
The great frequency with which Ascaris lumbricoides is found 
in the Philippine Islands and the unusual number of cases which 
have been reported recently in which the worms have been the 
direct cause of death or important secondary causes, through mi- 
gration into the liver or pancreas, makes the study of their 
development of considerable importance to us, for it is only 
through a knowledge of the development, whereby we may ob- 
tain knowledge of the means of infection, that we may expect 
to decrease or eradicate these worms in the Philippine Islands. 
It was with this idea in mind that the study of this interesting 
form was undertaken ; and, although my work so far has resulted 
in nothing of great moment, I think that some of the facts 
which have been obtained will be of interest. 
In my experiments I have depended almost entirely upon 
eggs laid in the laboratory by living worms which have been 
obtained from the morgue through the kindness of Dr. B. C. 
Crowell. It was found that if ascarids taken from the intes- 
tine are placed in Kronecker’s salt solution (normal salt solution 
to which 0.06 gram of sodium hydroxide per liter is added) 
they will remain alive and active for from six to twelve days 
and the females will generally lay a large number of eggs. 
To obtain the eggs for experiment, separate adult females 
were placed in glass dishes of the solution and each worm was 
removed into a fresh dish as soon as any eggs were laid. The 
majority of the worms laid eggs only two or three times, but 
some laid as many as eight times before dying. The female 
worms were always kept in the light during the daytime and 
the eggs were generally, although not always, laid at night. 
The eggs laid in Kronecker’s solution differ in no way from 
those which are found in feces. The commonest form is the 
typical oval egg consisting of a rounded mass of protoplasm 
*Read at the annual meeting of the Philippine Islands Medical Associa- 
tion, Manila, November 4—7, 1914. 
19 
