226 CHILD. [VOL. 1. 



protruded cirrus,/", which has probably been forced out through 

 the pore by the pressure during fixation. Here then is a complete 

 set of genital organs and a second partial set occurring without 

 any furrows between them. This condition is rare. I have found 

 only one other similar case. 



This appears to be a duplication of genital organs in a proglot- 

 tid which is morphologically single, at least in its right half. I 

 believe, however, that this case is simply another example of the 

 fact that a certain degree of individuality may exist without the 

 appearance of furrows, but may still be quite sufficient to lead to 

 the partial formation of genital organs. The fact that the pro- 

 glottid is divided on the left side into two parts by partial furrows 

 of normal depth affords additional evidence for this view. It is 

 evident that the causes leading to the formation of genital organs 

 at e and f is much less efficient than normally, for the organs 

 are extremely rudimentary and can never function in the normal 

 manner. 



The presence of furrows on the surface is, in general, simply the 

 morphological expression of certain internal conditions. These 

 relations differ in degree in different species, and, as is evident 

 from the variations discussed in this paper, in this species also. 

 This being the case, the logical conclusion seems to be that a 

 certain degree of isolation or individuality may exist without the 

 appearance of furrows on the surface. 



In this rudimentary and incomplete set of organs, e and _/", it is 

 seen that the two parts, e and f, arise independently of each 

 other. The pore and cirrus are absolutely unconnected with the 

 inner portions of the ducts which are present. These facts show 

 that the proximal and distal portions of the genital organs arise 

 independently in situ, in, or as nearly as possible in, the position 

 which is normal for each. 



The cells of the incomplete set show the same degree of dif- 

 ferentiation and the same reaction to the stain as the correspond- 

 ing regions of the complete set, g. It seems probable, therefore, 

 that both sets were formed at the same time. The differences 

 between the two sets consist in the entire absence from the one 

 of certain parts present in the other. As will appear below, a 

 segment of less than normal length usually possesses only partial 



