46 B. GEASSI AND A. SANDIAS. 



anterior is the smaller, and may show traces in its turn of 

 one or two transverse constrictions. 



The species is more commonly mammiform (shaped, e. g., 

 like the udder of a goat), with a small nipple-shaped anterior 

 process, which more or less resembles a teat, even when th© 

 general shape is not mammiform^ and will be briefly referred 

 to as the mamilla. 



The Protozoon, therefore, exhibits a mamilla and a base 

 from which it springs and appears to be delimited by an evident 

 constriction. This mamilla may be curved towards the body 

 in various ways, or may be spirally twisted. 



Most of the varieties of form here described appear to be 

 constant, and no change of shape is discernible under the 

 microscope. But this may be due to the unfavorable cir- 

 cumstances for observation, and it must be left undetermined 

 "whether this diversity of form is dependent on contractile 

 phenomena or not. 



The mamilla and the anterior half of the body are certainly 

 much more variable in form than the posterior half; and 

 Trichonympha in general is far more variable than Joenia. 

 In any case the mamilla is undoubtedly flexible. 



Both ectoplasm and endoplasm are distinguishable. The 

 ectoplasm of the mamilla and the anterior half of the body 

 may conveniently be spoken of as the striated zone (although 

 the apex of the mamilla is not striated) ; it differs from 

 that of the posterior half, which constitutes the unstriated 

 zone. The limit between these two zones may be median, or 

 may be situated at the junction of the anterior third or fourth 

 part of the body with the remainder. 



The striation of the striated zone is longitudinal, and clearly 

 due to the alternation of shallow sulci and ridges in the cor- 

 tical layer of ectoplasm ; that of the mamilla is coarser and 

 more remote than that of the body mass. The ectoplasm of 

 the striated zone usually appears dense and homogeneous, and 

 its inner layer is traversed towards the front of the body by 

 circular transverse lines ; their meaning is obscure, but they 

 are probably myonemes. 



