/// (III' Animal hiiKjilom. 307 



a quorition of exercising an asriimiiating influence upon tlio 

 yolk-niateiial. Tlic clianges undergone by the leucocytes and 

 follicle-cells during the absorption of the egg-cell, and espe- 

 cially tbe enlargement of the nucleus, the manifold forms of 

 the amitotic division, the occurrence of multinuclcar cells, 

 and tliC disintegration of nuclei, have recently been minutely 

 investigated by l\uge* in different Amphibia, lluge's ]:)aper 

 contains so many observations of importance for tlie question 

 before us that 1 must refer the reader to it, and cannot here 

 attempt to recapitulate his results in a few words. 



A very typical case is that which has been described by 

 Chun t- 111 the nectocalyces of the Calycophorid Siphono- 

 phora we find in the radial canals and in the anastomosing 

 oifshoots from them " the large flattened endoderm-cells filled 

 with a brood of nuclei." " The larger ones among them 

 rarely exhibit rounded contours; generally they show a band- 

 like or vermiform elongation, and are beset with lateral 

 ])apil!a\" " Sometimes dumb-bell- or biscuit-shaped nuclei 

 constrict into two equal halves, while at others the division of 

 the nucleus more resembles a budding, in so far as the nucleus 

 which is constricted off is considerably smaller, while the 

 larger nucleus simultaneously exhibits various proliferations, 

 wiiich likewise commence to constrict." " In no case does 

 the direct division of the nucleus in the Siphonophora entail 

 a subsequent division of the cell ; " Cliun lays special stress 

 upon this fact, " since, moreover, in all cases where direct 

 nuclear division has hitherto been shown to exist we get a 

 formation of multinuclcar cells, but no certain evidence of a 

 subsequent division of the cell." It appears to be probable 

 that the nuclei described by Chun possess an energetic physio- 

 logical activity of the kind mentioned above ; for the forma- 

 tion of the plexiform anastomosing offshoots of the radial 

 canals points to the fact that the epithelium of these canals is 

 destined to come into contact with the surrounding tissues to 

 the largest possible extent, and, as Chun asserts, is of great 

 importance for the metabolism of the musculature of the 

 nectocalyces which effects the swimming-motion. 



In many insects we find nuclei of quite remarkable size 

 in the nutritive cells, which collect round the egg-cell in 

 the ovary in order to supply it with nutrient material % | in 



• G. Rupre, " Vorgjinge am EifoUikel der Wu-beltiere," Morphologisclies 

 Jahrbuch, xv. Bd., 1890. 



t C. Ciniu, '• Ueber die Redeutung der direkten Kernteilung," Schrif- 

 ien der pbysikal.-okon. Gesellscbaft zii Kouigsberg i. Pr., 31 Jahrg., 

 1890. 



\ Compare also the figuie of tl.e large nutritive cells of Musca vomi- 



