EEPORT ON THK PENNATULIDA. 11)7 



increased considerably in size, and the component sperm cells are 

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

 a central space appears in the middle of the spermatosphere, which 

 has now a radiately striated aspect. Soon after this the spermato- 

 sphere becomes detached from its stalk and lies free in the polype 

 cavity. 



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

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

 than that of the egg ; and within this a very thin membranous coat ; 

 inside which are an enormous number of minute, oval, highly refractive 

 bodies, the heads of the spermatozoa, many of which have long tila- 

 mentary tails attached to them. In the centre of the spermatosphere 

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

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

 clearly distinguished under high powers of the microscope. 



Spermatospheres having this structure are found far forwai-d 

 in the polypes close to the moiiths 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 oi'der to satisfy ourselves 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 in stating that the sexes in I eunatula are distinct. 



We have also investigated for the same purpose and in the same 

 manner four specimens of I'ennatula in the Owens College Museum, 

 the result being to confirm the above conclusion in all cases. 



Our account of the male Pennatula will be found to agree very 

 closely with the description given by Kolliker* of the male in 

 HaJisceptnim, a genus belonging to the same family as Pennatula, and 

 differing from it mainly in possessing no calcareous spicules in the 

 leaves. Concerning the relative abundance of the two sexes, out of 

 six specimens of Ilalisce2)t)um examined by Kolliker, five were females 

 and only one a male ; while of the six specimens of Pennatula we 

 have had an opportunity of studying, two are females and ioxir males. 

 The close similarity, if not identity, in external form between the two 

 sexes, and also the close resemblance of the spermatospheres to the 

 ova, must make us very cautious about accepting statements concerning 

 the sexuality of specimens, unless it is explicitly stated that the 

 character of the genital products has been determined by the 

 microscope. 



* Kiilliker: Op. cit, pp. 1G4-167. 



