134 Miscellaneous. 



The three species that I have studied are CamjicinvJaria jlcxuosa, 

 Gonotliyra'a Loveni, and Podocoryne carnea. I selected these three 

 species for the purpose of following a course parallel to that which 

 I pursued in regard to the development of the ovum. The first has 

 its sexual generation represented by gonophores, which remain con- 

 stantly attached to the hydroid polype ; the second presents a semi- 

 medusa, and the third a free medusa. 



I find it impossible to share the opinion of those authors who 

 accept the ectodermic origin of the male sexual products in these 

 species. 



In Campanidaria Jle.vuosa we find in the endoderm of the stem 

 before the appearance of any gonophores, some large highl)--refrin- 

 gent cells ; these are the primitive mother-cells. They are I'ound, 

 and possess large nuclei with a nucleolus. The presence of a certain 

 numljer of mother cells induces the formation of a gonophore, 

 which is at first only a simple ca^cal diverticulum of the endoderm 

 and ectoderm. The endoderm of this diverticulum is thi;s occupied 

 by a certain number of mother cells ; and at this moment we can 

 ascertain that the intermediate lamella certainly passes over these 

 differentiated cells, and that consequently the origin of the testis 

 is certainly endodermic. 



It is very important, for the recognition of these facts, to observe 

 the gonophores as yoimg as possible, when the large mother cells, 

 which are known by their refringency, occupy the endodermic 

 wall of the bod}^ of the polype and are in immediate contact 

 with the digestive cavity of the colony, and when the csecal diver- 

 ticulum above mentioned begins to make its ajipcarance. In fact, 

 after this moment the primitive mother cells multiply rapidly, and 

 the daughter cells, which are much smaller and always j^ossess re- 

 fringent nuclei, form a testicular mass of a horseshoe form, which 

 very rapidly increases in si/.e. At the same time the testicular 

 mass ceases to form part of the endodermic wall, and to be in direct 

 contact with the digestive cavity of the colony ; for the non-difi'er- 

 entiated endoderm, previously interrupted at this point by the 

 testicular mass, becomes I'cconstituted beneath this mass, and there 

 forms a continuous layer. Thus, in consequence of this multipli- 

 cation of the mother cells and the reconstruction of an uninterrupted 

 endodermic layer beneath the testicular mass, it is very dilficult at 

 this moment to recognize the origin of the testis, which has become 

 an isolated mass, between the ectoderm and the endoderm recon- 

 structed beneath it ; and in consequence of there being this endo- 

 derm of new formation, which may be mistaken for the i)rimitive 

 endoderm, beneath the testicular mass, one may very easily supjiose 

 that the intermediate lamella passes beneath the mother cells, and 

 that therefore the origin of the spermatozoids is ectodermic. It is 

 this, I believe, that has led into error the authors who accept the 

 ectodermic origin of the male sexual products. 



In Gonothijraa Loveni the affair takes place in the same manner, 

 and I need not dwell upon it further. 



In Fodoconjne carnea, in the region of the body of the hydroid 



