in (he Aiiiiital Kingdom. 375 



connected with the lacunae of the dermal layer of the neck and 

 proboscis. Since the proboscis and the neck are buried in 

 the intestinal wall of the host, and the rest of the body in the 

 lumen of the intestine is surrounded by the contents of the 

 latter, nutrition can be carried on by means of the lacunar 

 system of the proboscis, the neck, and the lemnisci, as well 

 as that of the remainder of the dermal layer. The lacunar 

 system of the lemnisci has, moreover, a hydrodynamic 

 importance for the extension and retraction of the proboscis. 



According to Kiickenthal* direct nuclear division occurs 

 in the Annelids, in the " lymphoid cells," which float in the 

 body-cavity ; many of these cells contain two or four nuclei. 

 Kiickenthal considers that the direct division of the nucleus 

 is followed by division of the cell, and he believes that the 

 quadrinuclear cells divide into four uninuclear ones. Ac- 

 cording to his view the cells which have arisen in this way 

 apply themselves to the dorsal vessel and to the intestine, and 

 change into chloragogen-cells f, which then finally perish by 

 being set free and degenerating. It appears to me that the 

 question of the regeneration of the lymphoid and chloragogen- 

 cells is not yet completely explained by these observations. 



In the uterus of Mammals, in the processes which follow 

 the setting-in of pregnancy, especially in the formation of the 

 placenta, amitotic nuclear division occurs in various tissues. 

 We learn from the papers of Masius + and Minot § that in the 

 rabbit fragmentation of the nuclei and inultinuclear cells occur 

 in the degenerating uterine epithelium, and tliat in the endo- 

 thelium cells of degenerating walls of vessels large fragmented 

 nuclei and peculiar groups of nuclei, pointing to direct nuclear 

 division, are met with. 1 discuss these phenomena no further, 

 since it would be too difficult and would lead us too far astray 

 to investigate to what extent processes of absorption and 

 secretion are operating in these cases. 



'i'he cases of amitotic nuclear division which belong to the 

 doniain of the pathologists, especially the nuclear division in 



* AV. Kuclieiilhal, *'Ueber die lymplxoideu Zellen der Anueliden," 

 Jen. ZeitscbrifL f. Natiirw. 18 Bd., 1885. 



t This statement of Kiifkeuthal s contradicts Vedjovsky's ob.^ei-vatiou 

 (' System uud MDrphologie der Oiigochaten,' Prag, 1884, p. 112), according 

 to which the regeneration of the degenerating chlnragogen-cells proceeds 

 fn ni bni;;ll young cells which lie deep down between the large cells. 



\ J. JMasius, " De la Genese du Placenta cliez le lapin,"' Archives de 

 Biologie, t. ix., 1889. 



§ Ch. Sedgwick Minot, " Uterus and Embryo.— 1. Ifabbit ; II. Mau," 

 Journal of Morpliolngy, vol. ii., 1889, Boston, -S.ass. 



