THE EGGS OF ASCARIS LUMBRICOIDES 



By Lawrence D. Wharton 



{From the Zoological Laboratory, College of Liberal Arts, 



University of the Philippines) 



In the microscopical examination of faeces for the eggs of 

 Ascaris lumbricoides a number of atypical forms of eggs are 

 often found of which the origin has not been explained. In 

 numerous attempts to account for their presence, diiferent 

 authors have even suggested that the most atypical forms are 

 produced by another species of worm. While working in the 

 laboratory with live Ascaris, I have been able to obtain eggs in 

 large numbers, under conditions which serve to throw consider- 

 able light op the production of these atypical forms. In this 

 paper I shall describe the methods by which I have obtained eggs 

 from living Ascaris, the various forms of eggs which are found 

 in faeces and which may be obtained in the laboratory, and the 

 experiments in which the atypical eggs have been produced. 



I have been able very frequently to obtain living Ascaris lum- 

 bricoides from autopsies at the city morgue, through the kindness 

 of Dr. B. C. Crowell, of the College of Medicine and Surgery. 

 When the worms are placed immediately in Kronecker's solu- 

 tion,^ they live for from five to twelve days at the temperature 

 of the laboratory (25° to 35° C), and the females continue to 

 lay eggs for some days. To obtain eggs for experiment, healthy- 

 looking, adult females were placed, separately, in glass dishes 

 of the solution, and the dishes were covered with glass plates. 

 The solution was changed each day, and a record was kept of the 

 kind of eggs laid by each individual. No attempt was made to 

 keep them in the dark during the daytime, and I found that the 

 eggs were generally, although not always, laid at night. To 

 make sure that the females used in the experiments carried 

 fertilized eggs, they were generally taken from a host harboring 

 both male and female worms. In some cases a male was kept 



* Common salt, 6 grams; caustic soda, 0.06 gram; distilled water, 1,000 

 cubic centimeters. I do not consider this solution a very good medium for 

 Ascaris, but it is the most satisfactory one of which I know. If placed in 

 water, the worm absorbs so much that in about twenty-four hours the body 

 wall bursts and the Ascaris dies. 



Ill 



