Miscellaneous. 135 



polype where the medusas are to bud forth, we find the endodermic 

 wall occupied by large refringent cells ; these are the primitive 

 mother cells. Soon the endoderm and the ectoderm form a ctecal 

 diverticulum, into which the mother cells pass. This diverticulum 

 will become a medusa ; and the mother cells will occupy its endo- 

 derm ; the intermediate lamella passes over them. 



I will not enter into the details of the development of the me- 

 dusa, as I shall soon have the honour of laying before the Academy 

 a memoir upon this subject. It will suffice to say that after this 

 period the testicular mass grows rapidly, that the endoderm is re- 

 constituted in the form of a new uninterrupted layer beneath this 

 testicular mass, and that the mass of spermatozoids finally occupies 

 the manubrium of the medusa between the ectoderm, which has 

 become considerably thinner, and the newly-formed layer of endo- 

 derm already mentioned. 



To sura up, in these three species 



1. The male sexual products do not originate in the gonophores, 

 medusoid buds, or meduste, as has been supposed, but in the cceno- 

 sarc of the hydroid polype itself, as I have already shown to be the 

 case with the ovum. 



2. The primitive mother cells of the spermatozoids are derived, 

 like the ova, from difterentiated endodermic cells. 



3. Like the ova again, these mother cells pass into a diverticulum 

 of the walls of the body ; and this diverticulum by development 

 becomes a gonophore, destined to be always attached to the hydroid 

 polype, or a semimedusa, or a free medusa. 



4. The origin of the sexual products and their development there- 

 fore present a very great analogy in the male and female colonies. 



5. If we accept these facts as demonstrated, the gonophores, the 

 semimedusaj, and the racdusse in both the male and female colonies 

 can be regarded only as representing the sexual individuals ; and it 

 consequently appears that alternation of generations cannot be 

 accepted. — Comptes Bendus, December 12, 1881, p. 1032. 



On ilie Phenomena of Division in Euglypha alveolata and the Mono- 

 thalamous Rliizopods in yeneral. 13y Dr. Aug. Gkuber. 



The investigations of Dr. Gruber upon the phenomena of the 

 multiplication by division in Eiujlypha alveolata and other Mouo- 

 thalamous llhizopods reveal important facts in the historj- of these 

 creatures. They show especially how the envelopes of the body 

 being more or less supple or resistant, infiueuce the mode in which 

 division is effected. 



If we group the Monothalamia in accordance with the nature of 

 their covering, we may form a first category for those of which the v 

 carapace consists of little plates of various forms produced by the 

 sarcode of the animal itself. It is here that we must place the 

 species upon which the author has made the most complete investi- 

 gations. 



