/// ///'' AiuiHdl Ki ii(j(h>m. 37.3 



coniiccticl with the lacuiiaiof tlic dermal layer of tlic neck and 

 ))rnl)osci.s. (Since llie proboscis and the neck are buried in 

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

 hinien 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, nvireover, a hydrodynamic 

 inijiortance for the extension and retraction ot the proboscis. 



According to Kitckenthal* 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. 

 Kiickcnthal considers that the direct division of the nucleus 

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

 quadrinnclear cells divide into four uninuclear ones. Ac- 

 covdino- to his view the cells which have arisen in this way 

 a})})ly themselves to the dorsal vessel and to the intestine, and 

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

 benig set free and degeiierating. It appears to me that the 

 question ot the regeneration of the lymphoid and chloragogen- 

 cells is not yet completely explained by these observations. 



Jn 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 j\lasius + and Minot § that in tlie 

 rabbit fragmentation of the nuclei and multinuclear cells occur 

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

 thelium cells of degenerating walls of vessels large fragmented 

 nuclei and peculiar groups of nuclei, pointing t ) direct nuclear 

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

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

 to investigaie to what extent processes of absorption and 

 secretion are operating in these cases. 



Ihe cases of anntotic nuclear division which belong to the 

 domain of the pathologists, especially the nuclear division in 



* AV. Kuclienthal, " Ueber die lymplioiden Zellen der Anuelideii," 

 Jen. Zeitschrift f. ^'aturw. 18 Bd., I880. 



t This statement ot Klickeuthal s contradicts Vedjovskv's observation 

 (' System nnd Mdrphob gie der Uiipochaten,' Prag, 1884, p. 112), according 

 to which the regeueiation of the degenerating chloragogen-cells proceeds 

 ir( ni snii.ll voung cells ■which lie deep down between the large cells. 



X J. MaJus, " De la Genese du Placenta chez le lapin," Archives de 

 Biologie, t. ix., 18*9. 



§ Ch. Sedgwick Minot, " Uterus and En:bno.— I. Pabbit : 11. Mau," 

 Jom-nal of Movplioh gy, \u\. \\., ls<^i>. Bof-tou, .\_ass. 



