ABNORMALITIES IN CESTODE MONIEZIA. 



same amount of growth here as at the lateral margins, while the 

 central parenchyma shows very little relative increase in thick- 

 ness. 



In general, the central parenchyma grows chiefly in the lateral 

 and longitudinal directions, the actual increase in thickness being 

 much less than the increase in other dimensions and relatively 

 very slight. The growth of the peripheral parenchyma increases 



O 



FIG. 69. FIG. 70. 



in amount from the anterior to the posterior end of each proglot- 

 tid, but is similar about the whole circumference of the body. 

 The first traces of the posterior extensions of the proglottids are 

 seen in Fig. 7 1 , a sagittal section of an early stage. Nearly all 

 the nuclei of the peripheral parenchyma are grouped near the 

 posterior boundary of each proglottid, indicating that growth is 

 more rapid there than elsewhere, and the outlines of the proglot- 

 tids are no longer regularly rounded, as in Fig. 59 for instance, 

 but show distinctly localized growth in the posterior region. 



The above observations upon the origin and growth of the 

 proglottid may be summed up as follows : The whole neck is a 

 region of growth ; in the anterior part of the neck the growth 

 is general but posteriorly it gradually becomes localized and thus 

 gives rise to the proglottids. Each proglottid arises as two dis- 

 tinct aggregations of nuclei in the central parenchyma near the 

 lateral nerve-cord. Gradually the intervening portions of the 

 central parenchyma come to show a similar arrangement and a 



zone of localized growth is formed. 



This growth next extends 



