256 SUMMARY OF CURRENT RESEARCHES RELATING TO 



curious to observe that the mode of budding exhibited by these last is 

 like that of the entire colony. As the so-called " Hauptzooid " is not 

 the primary polyp, but a secondary zooid, the term is a misnomer. 

 Finally, we have to note that the posterior part of the body of the 

 primary polyp persists as the peduncle of the colony. 



Development of Campanularia angulata * — M. J. Fraipont has a 

 fuller account, illustrated by three plates, of his investigations on 

 this subject, of which an account has been already given.f 



Development of the Ova of Eudendrium.ij: — Dr. N. Kleinen- 

 berg is not satisfied with the evidence adduced by Goette § as 

 to the endodermal origin of the ova of this Hydroid ; he believes 

 that the ectodermal cells may wander into the endoderm. He 

 has always seen the generative cells derived from the ectoderm ; 

 where, the difficulties of observation have prevented this, they have 

 likewise prevented him from coming to any definite conclusion at all. 

 In no case has he proof of endodermal cells being converted into 

 generative cells. Against the definite results of E. van Beneden, he 

 can only say that the use of acetic acid is very likely to lead to wrong 

 conclusions. He cannot understand how Weismann failed to detect 

 the presence of ovarian cells in the ectoderm, unless he examined the 

 animal after its most active stage. Many Hydroids exhibit a well- 

 marked periodicity in the development of their generative products ; 

 those that are formed during the intermediate periods are often abor- 

 tive or variously abnormal. Developed embryos, unfertilized ova, ripe 

 spermatozoa, and young sperm-cells may all be found in the same bud. 

 Eudendrium is most active reproductively at the beginning and at the 

 end of summer. 



Porifera. 



Sponges of Russia.] | — Dr. W. Dybowsky, who seems to have ob- 

 tained a large amount of material for the study of this subject, has 

 made extensive use of dry specimens, finding that this method is quite 

 sufficient for systematic determinations of the siliceous forms, and 

 considering, as he does, that in the Halichondrice (Schmidt) the 

 skeleton is the only part which is important in this respect. The plan 

 adopted for preparing dried sponges for the Microscope, is to boil a 

 thin section in alcohol, until the liquid becomes cloudy owing to the 

 incipient solution of the parenchyma ; concentrated solution of potash 

 (more or less, according to the proportion of horny matter in the 

 skeleton) is now added, and the whole warmed until of a brown 

 colour ; the fragments are then removed and boiled again in alcohol, 

 by this means much of the parenchyma is removed ; the residue is 

 teased and stained for a few minutes in alcoholic solution of eosin, 

 which colours only the remaining horny substance ; creosote, or oil of 

 cloves, or a mixture of both, is used to render the preparation trans- 

 parent, and it is then mounted in Canada balsam. For the study of 



* Arch. Zool. Exper. et Gen., viii. (1880) pp. 433-67 (3 pis.). 



t See this Journal, ill. (1880) p. 459. 



X Zeitschr. wiss. Zool., xxxv. (1881) pp. 326-32. 



§ See this Journal, ill. (1880) p. 812. 



il Mem. Acad. Impe'r. St. Petersburg, xxvii. (1880) No. 6, pp. 1-71 (4 pis,). 



