132 David Day Whitney 



thirds of the gray zone and a portion of the clear zone (Fig. 6). 

 On March 11, at 11 a.m., a normal young female was swim- 

 ming about in the dish. Food was added. This female matured 

 and produced fifteen eggs which developed into females. One 

 of these daughter-females produced males and the other fourteen 

 produced females. 



Experiment LV. The conditions, size of egg and the arrange- 

 ment of the egg material in the first cleavage were approximately 

 the same as in Experiment L. A normal young female developed 

 from the egg, matured and produced fourteen eggs all of which 

 developed into female-laying females. In later generations 

 males appeared. 



Several small male eggs were centrifuged in the same manner 

 as the large eggs. In some of these the first cleavage plane appeared 

 so as to cut off all the pink zone in the small cell and in others it 

 cut off some of each of the three zones. In both cases apparently 

 normal males were produced. 



None of the females in the above experiments produced the 

 normal number of eggs, which is forty to fifty, because of poor 

 food conditions. 



In former experiments it has been shown that the percentage 

 of male-laying females in a family of daughter-females may vary 

 from o to 50 per cent and also that the percentage of male-laying 

 females in one generation is no indication what it may be in the 

 next generation. 



Experiments XXXI to LV. In these experiments the appear- 

 ance of male-laying females from the various forms of centri- 

 fuged eggs does not seem to be markedly different from normal 

 cases. In the experiments where the daughter-females of a family 

 were all female-laying females males always appeared in the 

 later generations, thus showing that no pure female-laying female 

 strains were produced. Moreover, large (female) eggs never 

 produced male animals nor did small (male) eggs ever produce 

 female animals. 



