NUCLEAR VOLUME AND LIFE-CYCLE OF HYDATINA 297 



All that appeared unhealthy, even if they still had eggs in the 

 oviduct, were rejected. 



The three lots of female-producers, young, middle-aged, and 

 old, were sectioned 5/i in thickness and stained with iron hema- 

 toxyHn and eosin. 



Since the middle-aged females are more likely to have male- 

 producing offspring than either the young or old ones, their 

 Kemplasmarelation should, according to Hertwig's theory, be 

 greater than that of the latter two. The results obtained are 

 described later. 



Effect of manure solution. A number of female-producers of 

 approximately the same age, taken at twelve to twenty-four 

 hours after egg-laying began, were divided into two lots. One 

 lot was continued in spring water, the other was put into strong 

 manure solution. Twelve to twenty-four hours later, both lots 

 were fixed in Bouin's fluid. They were sectioned 5fj, in thickness 

 and stained with iron hematoxylin and eosin. 



Since manure solution almost immediately reduces the number 

 of male-producers, the females treated with manure solution 

 should, on Hertwig's theory, have a smaller Kemplasmarelation 

 than those reared in spring water. 



Tissues examined for Kemplasmarelation. Hertwig and Issa- 

 kowitsch appear to have considered only the Kemplasmarelation 

 of the germ cells as important in determining the life-cycle. 

 Papanicolau, as pointed out above, employed intestinal cells, and 

 Hartmann used also hypodermis and gangha. In the rotifers 

 I was encouraged to use other tissues than the oocytes for two 

 reasons. First, the occurrence of males is determined a whole 

 generation in advance of the actual production of male eggs, so 

 that any change in the Kemplasmarelation might be detectible 

 in the somatic cells of at least the male-producing parents. 

 Second, since the alteration of the Kemplasmarelation is sup- 

 posed to be a metabohc (essentially a nutritive) phenomenon, it 

 seemed not unhkely that organs concerned with nutrition would 

 show similar alterations. Two such organs are the yolk gland 

 and the stomach-intestine. The egg, in passing do"wn the ovi- 

 duct, is lodged in the angle between the yolk gland and stomach- 



