458 A. FRANKLIN SHULL 



intestine, with which they are connected by short canals. 

 They are hkewise syncitia, which jNIartini finds always contain 

 six nuclei. 



Detennination of the number of nuclei in these glands was 

 made from serial sections. The sections had been prepared for 

 another use in which it was important to have complete series. 

 All imperfections in the series were therefore recorded, and for 

 the counting of nuclei only complete series were used. More- 

 over, in the yolk gland, the nuclei are so large that five or six 

 successive sections passed through each nucleus, so that any 

 breaks in the series large enough to omit one nucleus would be 

 easily detectible not only from the yolk gland itself, but from 

 the surrounding tissues. In the case of the gastric gland, the 

 nuclei are smaller, and, though imperfections in the series of 

 sections could probably have been detected from the sections 

 themselves, reliance was placed entirel}' upon the records made 

 when the slides were prepared. In any case, incompleteness 

 in the series of sections could ne\'er lead to an erroneous increase 

 in the number of nuclei counted. All aberrant numbers were 

 determined independently by two persons trained in the interpre- 

 tation of serial sections, and in every case there was agreement. 



YOLK GLAND 



This organ was examined in two hundred and forty-five satis- 

 factory individuals. In two hundred and thirty-five, the number 

 of nuclei was eight. In the remaining ten, a trifle over 4 per 

 cent of the total, aberrant numbers were found, as indicated in 

 table 1. 



TABLE 1 

 Distribution of the numbers of nuvlei in the yolk glands of £45 specimens of Hydatina 



senta 



