The anatomy of a pteropod, Corolla (Cymbuliopsis) spectabilis Dall. 77 



As the figures show only half of the cells of the lens undergo 

 this metamorphosis. The remainder, for a long time unchanged, are 

 distinctly visible near the center of the lens but as the final stage 

 in the formation of the main fluid cavity of the lens is reached they 

 show signs of degeneration. Their chromatin becomes exceedingly 

 dense and contracted, the nuclear membrane grows irregular in out- 

 line, the cytoplasm surrounding them apparently dissolves so that in 

 the final stage in the development of the eye-spot this group of cells 

 is represented by merely a few shrunken remnants usually disposed 

 on one side of the lens. 



The Reproductive System, 



The reproductive system consists of the ovary and the accessory 

 glands, the latter forming a cap on the anterior end of the visceral mass 

 on the ventral side of the oesophagus. The ovary is composed of a 

 relativley thin sheet of cells investing the visceral nucleus, with the 

 exception of the region of the stomach. It is surrounded by a thin 

 brownish pigmented membrane that divides it into several relatively 

 large follicles. Externally this membrane adheres very closely to the 

 ovary but on the inner side it is more or less separated from it 

 leaving spaces that become larger towards the anterior end of the 

 visceral mass where they connect with the oviduct. Into these spaces 

 the mature sex products are dehisced and are then carried forward 

 to the oviduct and from thence to the exterior. 



As just mentioned the irregular spaces of the ovary become con- 

 tinuous with the single oviduct that is situated on the underside of 

 the reproductive cap near to the oesophagus (Fig. 10 ovd.). A short 

 distance beyond its point of union with the ovary the oviduct bends 

 sharply and passes between the lobes of the muciparous and albumini- 

 ferous glands through which it continues to run until it reaches the 

 right side of the cap where it bends abruptly away from the oeso- 

 phagus. Here the seminal receptacle {s.r.) is attached and immedi- 

 ately beyond the oviduct becomes dilated into the so-called uterine 

 portion {ut), the walls of which are thrown into many folds all of 

 which bear cilia whose size and abundance varies considerably. 



Beyond the uterine portion the oviduct becomes again narrowed 

 into a relatively slender canal that turns sharply back upon itself and 

 extending toward the oesophagus passes over the muciparous gland 

 to the external opening. In this latter part of its course the oviduct 

 receives two short ducts communicating with the muciparous gland. 



