LIFE HISTORY OK ASCJARIS LUMBRICOIDES. 5 



left exposed to the sun in India for G weeks contained actively motile 

 ombi-yos at the end of that time. AVe have kept the eggs of Ascans 

 i^uiim in an incubator at 37*^ ('. until they became extremely dry, but 

 tliere was no c-ontinuation of the development when the eggs were 

 moistened and removed to a lower temperature. Though dryness 

 may be fatal to the eggs of Ascaris, it is certain that under most 

 climatic ccmditions there is sufficient moisture in the environment 

 (usually the soil) into which the eggs come after elimination from 

 the host to enable development to proceed, at least intermittently, 

 if not continuously. The inhibiting effect of the lack of moisture 

 and the stimulating effect of its presence may be easily observed by 

 placing new^ly deposited A semis eggs in water on a slide under a 

 cover glass, noting the stage of development and then allowing the 

 preparation to dry naturally. In a few days, if w^ater is added to 

 the preparation, little or no further development will be seen to 

 have occurred, but if the slide is kept moist for a few days it will 

 be found that development proceeds again. By moistening or drying 

 development may be thus favored or hindered. 



As shown by Hallez (1885), oxygen is necessary to the development 

 of Ascaris eggs. This is indicated by the fact that eggs in water 

 covered by a film of oil fail to develop. We have observed that if 

 the eggs are kept in stoppered bottles filled with water development 

 is inhibited. According to Faure-Fremiet (1912), the determining 

 cause of segmentation is the oxidation of hydrocarbon reserves stored 

 up in the ^g^g.^ for wdiich, of course, a supply of oxj^'gen is necessary. 



Bacterial decomposition of the surrounding medium inhibits de- 

 velopment and may be destructive to the vitality of Ascaris eggs. 



INCUBATING ASCARIS EGGS FOR EXPERIMENTAL USE. 



To secure the rapid development of a high percentage of Ascaris 

 eggs to the final stage for experimental purposes, various methods of 

 incubation have been used by different investigators. Martin (1913) 

 obtained the most satisfactory results by placing the eggs in a 2 

 per thousand solution ' of hydrochloric acid and incubating at a 

 temperature of 33° C. Hallez (1885) spread the eggs over the sur- 

 face of earth in a flowerpot which was kept moist by standing in 

 water. After trying various methods and media we have adopted 

 the following: The adult worms after collection are sorted by sex 

 and size and only the larger females are retained. These are slit 

 lengthwise and pinned out in a tray of water. The uteri are dis- 

 sected out and removed. Twenty worms will furnish all the eggs 

 that can be incubated in three petri dishes 13.5 centimeters in 

 diameter. The uteri are snipped with scissors into as small pieces 

 as possible and are then rubbed up with a small quantity of 2 per 

 cent formalin in a glass mortar. This forces the eggs out of the 



