The Histogenesis of Cysticercus pisiiormis. 239 



differentiated granular cytoplasmic mass. In Fig. 5 the developing 

 nuclear membrane shows three enlargements which are identical in 

 appearance with the deeply-staining granules already described, 

 indicating a similarity of origin for both. If then, the granules, as 

 I hope to show later, originate in the cytoplasm, the nuclear mem- 

 brane presumably arises in a similar fashion. In this connection 

 compare also the cell figured at x in Fig. 6. The nuclear granules 

 usually arise before the nuclear membrane as described above but 

 the two may arise simultaneousl3% or the membrane may even take 

 precedence of the granules {x Fig. 33). 



This spontaneous method of cytogenesis, if one may associate 

 the terjn spontaneous with biological phenomena, is not restricted 

 to the larva, but occurs likewise in the adult Taenia. An instance 

 of this is shown in Fig. 34 where are seen two flame cells 

 developing from a cytogenetic protoplasmic mass. Fig. 49 represents 

 another of these masses lying in and forming part of the parenchyma 

 syncytium, while in Fig. 46 is shown a probably similar cell mass 

 from which are developing three sub-cuticular cells. 



The difference in staining reaction between the sub-cuticular 

 and parenchyma cells has been urged by both Blochmann (1897) 

 and Hein (1904) as evidence of a specific difference between these 

 two tissues. I maintain that this is a misinterpretation of observed 

 facts and that these difterences are rather of physiological than of 

 morphological import. Rössler (1902) has pointed out that in passing 

 from the bladder wall to the neck and scolex in Cysticercus 

 fasciolaris and tenuicollis the nuclei change their appearance, 

 becoming progressively more deeply stained. And this observation I 

 can verify in Cysticercus pisiformis. The change is a gradual 

 one. Accompanj'ing the elongation and increase in size of the cells, 

 the nuclei maintaining approximately the same size, but becoming 

 oval in shape, the cytoplasm becomes continually more densely 

 stained and the nucleoplasm likewise, the two approaching each 

 other more nearly in density until finally a distinction is no longer 

 observable, the cell body staining with uniform density thruout. 

 A comparison of Fig. 51 with Figs. 45 and 50 will make this 

 difference clear to the reader at a glance. This phenomenon is not 

 of occasional, but of general occurrence. 



In the adult sub-cuticula, varying conditions are encountered. 

 Occasionally the nucleus of the sub-cuticular cells is plainly dis- 

 cernible (Fig. 47 and sc:c Fig. 48); in other preparations the cell 



