ON BUDDING IN POLYZOA. 529 



The history of the other organs need not detain us; it is not 

 stated from which of the two primitive tissues they are second- 

 arily derived. 



Salensky's account presents us with fewer difficulties than 

 that of Vogt, V)ut while agreeing with him as to the epiblastic 

 nature of the outer layer of cells, I would suggest that the central 

 cell, which he thinks is of the -same value but does not prove it, 

 is really derived from the alimentary canal of the parent, and 

 is therefore hypoblastic. It is also possible that the involution 

 which he describes, but on which he does not lay much stress, 

 really forms the intra-tenacular space, as his account of the 

 formation and position of that cavity appears to ine to warrant 

 that supposition, and that his (epiblastic) endoderm developes 

 only into the stomach and intestine. 



Hincks in his abstract of this paper (10), says : " I am quite 

 unable to harmonise the account given by the author of this 

 portion of the developmental history with that which we have 

 from Vogt." 



It will probably be found that the harmonizing of these 

 and other accounts is possible according to the views stated 

 above. 



Prof. Oscar Schmidt (5) has propounded the original view 

 that the bud in Loxosma cochliaris formed parthenogeneti- 

 cally from an egg, and that it is therefore not a true bud but an 

 embryo ! His paper is accompanied by a plate which is too 

 sketchy to be of any value whatsoever. Nitsche and Salensky 

 overthrow this theory, and the latter points out that buds in 

 which no ovaries are developed may give rise to secondary buds, 

 thus precluding any possibility of a parallelism between the bud 

 of a Loxosoma and the ovicell of one of the Ecto procta. 



Nitsche (4) has studied the gemmation of Loxosoma 

 Kefersteinii. In this form he asserts that the bud originates 

 from a grouping together of one or two ectoderm cells, these 

 divide and form a single layered ring round one central cell. 

 This latter, which he calls the " Endodermzelle," divides into 

 two, then into four, and altimately forms a mass of cells which 

 acquires a central lumen, and by subsequent constriction differ- 



