PENNATULA PHOSPHORKA. 46 



exaiuiuuiji them with high powers (i^. in. and jJ„ in.), that we discovered 

 their real nature. 



Like the eggs iu the female, the male organs are developed on the 

 edges of the septa, which bear, higher up, the short thick mesenterial 

 tilameuts. So far as we have been able to determine only four of these 

 six septa bear these oi'gaus, namely, the dorsal and ventral pairs of 

 each polype-cavity, the pair belonging to the under surface of the leaf 

 being, as a rule, if not indeed constantly, sterile. 



As in the female the reproductive organs are borne by all the leaves 

 except the very youngest, and by all the polypes of each leaf, being far 

 more abundant in all stages of development at the basal ends of the 

 polypes than towards their free extremities. 



Iu the earliest stages of development that we have noticed, the 

 male orgaus (Figs. 4 and 5, ts) are small knobs composed of spherical 

 nucleated cells, surrounded by a capsule of flattened epithelial cells, 

 aud attached to the edge of the septum by a short stalk. 



In the next stage, the spermatosphere, as we may call it, has 

 increased considerably iu size, aud the component sperm cells are 

 far more numerous though of smaller size than before. A little later a 

 ceuti'al space appears iu the middle of the spermatosphere, which has 

 now a radiately striated aspect. Soon after this the spermatosphere 

 becomes detached from its stalk and lies free iu the polype-cavity. 



It is now a spherical body with an average diameter of 0'014in., 

 aud consists of an outer cellular capsule much thinner and less tough 

 than that of the egg; withiu this is a very thin membranous coat, 

 inside which are an enormous number of miuute oval highly refractive 

 bodies, the heads of the spermatozoa, mauy of which have loug fila- 

 mentarj- tails attached to them. In the centre of the spermatosphere 

 is a clear space iu which no sperm cells or heads of spermatozoa are 

 present, but in which the thread-like tails of the spermatozoa cau be 

 clearly distinguished under high powers of the microscope. 



Spermatospheres having this structure are found far forward 

 in the polypes close to the mouths through which they undoubtedly 

 escape ; but whether the spermatospheres break up on escaping from 

 the polype into their constituent spermatozoa, or remain for a time in 

 the condition described above, we have been unable to determine. 

 We have seen no indication of a tendency to break up in any of the 

 spermatospheres, and yet these have no inherent power of locomotion 

 for the epithelial capsule enclosing them is not ciliated. 



In order to satisfy oui'selves as to whether the sexes are really 

 distinct, we have examined the reproductive organs from about a dozen 

 different leaves of each of the specimens, selecting leaves from both 

 sides and from very various parts, with the result that all the leaves 

 examined of the one specimen bear male organs and of the other female ; 

 from which we feel justified in concluding that Lacaze-Duthiers is 

 correct iu stating that the sexes iu Fennatula are distinct. 



