ABNORMALITIES IN CESTODE MONIEZIA. 145 



glottid wholly separated from all others by furrows will probably 

 be formed (V. g. t Fig. 18, Pt. I.). These variations consisting of 

 half-proglottids or smaller fractional portions cannot be sharply 

 separated from the preceding group in which both halves are* 

 present, but imperfectly defined. As is evident from the figures, 

 all gradations occur. The one extreme approaching the normal 

 condition consists of two or more well-defined proglottids with 

 scarcely interrupted furrows (c. g., Fig. 12, Pt. I.). In many 

 other cases both halves of each proglottid are present, as indi- 

 cated by the genital organs, but those of one side, right or left, 

 are not sufficiently distinct to cause the appearance of normal 

 furrows (e. g., Figs. 11 and 16, Pt. I.). In most of these cases 

 one of the imperfectly separated halves is reduced, the reduced 

 portion being always the anterior, /'. e., the later in time of 

 formation (Figs. 10 b, 16, 17, 19, 21, 22 c and d, Pt. I.). The op- 

 posite extreme is reached in those cases where the proglottid 

 appears only on one side of the body, not being represented in 

 any way on the opposite side (Figs. 9 and 18, etc., Pt. I.). 



It should be noted that all imperfect or partial proglottids 

 occur either in the right or left half of the body or in both, never 

 in the middle region only. This fact must be interpreted as indi- 

 cating that they are the result of imperfect development either 

 of the right or left proglottidal anlage or of both. If the normal 

 proglottid were formed by simultaneous differentiation and growth 

 all the way across the body, there seems to be no good reason 

 why abnormalities should not appear near the median line without 

 reaching the lateral margins as often as they occur in the right 

 or left side. Each proglottid arises, however, from two distinct 

 anlagen placed laterally in the central parenchyma and these 

 unite secondarily at the median plane. Therefore the conditions 

 near the median plane must depend upon the development and 

 growth in lateral regions. On the other hand it will be observed 

 that none of the variations are confined to the extreme margin of 

 the body. All include the region which was occupied by the 

 group of nuclei at the time of proglottid-formation. In the 

 figures this region lies slightly lateral to the ovaries. 



It is evident that all the facts concerning position, form, extent, 

 and distinctness of the imperfect and partial proglottids harmonize 



