ABNORMALITIES IN CESTODE MONIEZIA. 157 



parts in adjacent normal proglottids, so that it is possible to 

 determine in the older proglottids just what parts are represented 

 in each case. Evidently then there is no great amount of retar- 

 dation in development in the partial or otherwise abnormal pro- 

 glottid. Organs once formed develop with the same rapidity as 

 those under normal conditions. What is lacking in these abnor- 

 mal proglottids is the initial stimulus or the proper condition for 

 the. formation of this or that portion. The structure of each ab- 

 normal proglottid is as complete as possible for that particular 

 form of proglottid. Organs are formed at the same time as in 

 other proglottids and those organs which do not appear at the 

 normal time are not formed later. There is no decrease in the 

 rapidity of development, there is simply the presence or absence 

 of a certain form and correspondingly the presence or absence of 

 a certain structure. 



In Figs. 3741 (Pt. II.) variations of another sort in the re- 

 productive organs are shown. Figs. 37 and 38 both show cases 

 of transverse duplication of portions of the reproductive organs 

 on one side of the body. This abnormal condition does not find 

 a satisfactory explanation in the form of the proglottid. All 

 that can be said at present concerning it is that for some reason 

 an extra growth-center, or perhaps more than one, is formed. 

 In the two cases cited this gives rise only to female organs, in 

 one case (Fig. 38, b] to a small imperfect ovary and a few groups 

 of cells representing the vitellarium, in the other (Fig. 39, c) to 

 these organs, and, in addition, a small blind seminal receptacle. I 

 have been unable to discover any clue to the causes concerned 

 in the formation of these supernumerary organs. 



In Figs. 40 and 41 (Pt. II.) three cases of reversal in position of 

 the lateral organs appear. In Fig. 40 the organs of the right side 

 are reversed in proglottid b, and in d those of the left side. In 

 Fig. 41 another case of the same kind occurs. This peculiar 

 variation is evidently correlated with the abnormal form of the 

 proglottids. It is, however, difficult to understand why a rever- 

 sal should occur in these cases, and not in others where condi- 

 tions are closely similar. It does not seem probable that these 

 variations indicate a " reversal of polarity " in those parts of the 

 proglottids containing them. Considerable variation in the posi- 



