104 S. GOTO. 



the remnants of the original epitheUum of the ovary. When the 

 ovary is more or less elongated the zones of formation and growth can 

 be very clearly distinguished ; the maturation of the ovum taking 

 place probably after its enclosure in the egg-shell. In Microcotijle and 

 in most species of Axine (Pis. I, II, & VII) the ovary is more or less 

 S-shaped when looked at from the dorsal side of the body ; in some 

 species the lower half of the S is drawn out almost straight, while in 

 some others this portion is coiled spirally on itself (PI. II, fig. 6). 

 The formative zone is situated at the posterior end of the ovary, and 

 looks in sections as a continuous mass of homogeneous protoplasm in 

 which numerous nuclei lie imbedded. These are provided with a 

 distinct membrane and contain numerous granules of chromatin. As 

 we proceed away from, tliis into the growing zone the protoplasm 

 becomes more and more distinctly separated around each nucleus, 

 or, in other words, the ova gradually acquire their independ- 

 ence ; the nuclei become larger and larger, the chromatin granules 

 become more and more undefined, and a distinct nucleolus makes its ap- 

 pearance in each nucleus; until finally in the terminal part of the 

 ovary, i. e., in that part where the oviduct takes its rise, each 

 ovum is provided with a large, clear, thin-wallel, vesicular nucleus 

 containing, besides numerous, faint, minute granules of chroma- 

 tin, a single large nucleolus, which takes up all stains with extreme 

 avidity and encloses a single large or several smaller vacuoles 

 (PI. IV, figs. 8 & 9 ; PL VII, fig. 3 ; PI. IX, fig. 6 ; PL X, fig. H ; 

 PI. XV, fig. 6 ; PL XVIII, fig. 6 ; PL XIX, fig. 13). In Axine 

 aherrans (PL VII, fig. 5) and in Octocotyle (PL IX) the ovai-y is an 

 elongated, cylindrical body which is bent on itself at its middle, 

 so that its ends come to be apposed to each other, and which 

 is placed with its long axis parallel to that of the body. In 

 Galicotyle (PL XIX, fig. 1) too it is a very long, slender body bent on 



