138 



A. RICHARDS. 



chymal nuclei suggests that they have divided. Still a third 

 line of evidence is obtained by a study of the number of nuclei in 

 given regions before and after the formation of the anlage. To 

 make such a study it is not sufficient to count the nuclei in a 

 single section of each proglottid and compare the counts directly, 

 for the proglottid grows in three dimensions. Either the entire 

 number of nuclei in all the sections to be compared must be 

 counted or the ratio determined by a mathematical calculation 

 based upon counts from different fields of the two sections, meas- 

 urements of the inner parenchymal ellipses (that part of the 

 parenchyma enclosed by the circular muscle layers) and the 

 number of sections of the proglottid. 



Such a calculation has been made and its results are given in 

 the following table. While the problem does not lend itself fully 

 to the rigor of a mathematical treatment, it is believed that the 

 results are approximately accurate, at least sufficiently so for 

 the sake of a comparison. In each case two proglottids from the 

 same chain, one near the head, the other farther back, are com- 

 pared; by nuclear ratio is meant the ratio of the number of 

 nuclei within the circular muscle layer of the one to that of the 

 other; the volumetric ratio represents the ratio of the volumes 

 of the parenchyma within the muscle layers for the same pro- 

 glottids. 



