X, D, 2 Wharton: Eggs of Ascaris lumbricoides 115 



resulted. I kept these eggs from a number of different indi- 

 viduals and found that they developed in the same manner and 

 in the same length of time as the typical eggs. In fact, it was 

 impossible to find any difference between the two kinds of eggs 

 except the total absence of the albuminous layer in the second 

 form. As this layer of the shell is produced only in the anterior 

 part of the uterus after the chitinous layer has been deposited, 

 its absence has no effect on the protoplasm of the egg. The 

 absence of the albumen from the surface must be due to some 

 physiological condition which prevents the formation and depo- 

 sition of the required substance by the uterine glands. What 

 this condition is I am unable to state. That it is not due solely 

 to a lack of nutritive material in the solution is indicated by the 

 fact that eggs of this form are sometimes found in the fseces 

 of perfectly healthy well-nourished persons, while in poorly 

 nourished and diseased persons the eggs may all have the typical 

 mammillated layer of shell. Although this experiment fails to 

 show why these atypical eggs are produced, it conclusively shows 

 that they are produced by Ascaris lumbricoides, if the proper 

 conditions arise, and that their presence in the fseces is not due 

 to the presence of any other species of worm or any particular 

 variety of Ascaris lumbricoides. 



In addition to the above-mentioned forms, unfertilized eggs 

 are also frequently found. These may be distinguished readily 

 by the fact that the protoplasm of the egg is not surrounded 

 by a vitelline membrane and completely fills the shell. It is also 

 much more vacuolated than in the fertilized eggs. The shell of 

 the unfertilized eggs may present any of the conditions found 

 in the fertilized eggs. In addition, both layers of the shell are 

 sometimes absent in the unfertilized eggs laid in Kronecker's 

 solution, but eggs in this condition are not likely to be found in 

 faeces as they would be destroyed very quickly by the juices of 

 the intestine or by the pressure of its contents and would not 

 succeed in passing out unbroken. 



