ABNORMALITIES IN CESTODE MONIEZIA. 147 



Fig. 9 (Pt. I.) for instance, the only difference being that in case 

 of a spiral the fractional proglottid unites with different pro- 

 glottids on the two sides of the body. It appears probable that 

 in such cases a slight difference in time of formation of the 

 dorsal and ventral portions of the proglottid is the cause of the 

 spiral condition. As was pointed out above, the relation of partial 



Fie. 72. 



proglottids to the proglottids posterior or anterior to them probably 

 depends largely, if not wholly on the time of their formation. If a 

 partial proglottid is formed at the same time as the next posterior 

 proglottid, i. t\, a little before normal time, the two will probably 

 be incompletely separated. If the formation of the partial pro- 

 glottid is retarded slightly it will probably become united with the 

 proglottid anterior to it. And lastly, if the time of formation of the 

 partial proglottid does not correspond to that of any other it will 

 probably be distinct from all others. Applying the same con- 

 clusions to the spiral partial proglottids (c. g., Fig. 72) it appears 

 probable that one side of the partial proglottid the dorsal (upper) 

 side of b in the figure is formed at about the same time as the 

 proglottid posterior to it, whereas the ventral (lower) side corre- 

 sponds in time of formation with c and so becomes united with it. 

 Recalling the method of formation of the proglottid, it is easy to 

 see that such differences in time of development of different parts 

 are at least theoretically possible. The localization of growth, 

 which is the essential feature of proglottid-formation, may for some 

 unknown reason appear somewhat earlier on one side than on the 

 other, just as it appears earlier in the lateral than in the median 

 regions of the central parenchyma. 



If now the dorsal and ventral sides of a series of anlagen on 

 either the right or left side of the body show similar differences 



