;^24 ^- ISHIKAWA. 



Last of all, the part played by the archoplasm in the formation of 

 the cilia in Noctiluca deserves some attention. Stni si mrger in Yns 

 Histologische Beiträge, Heft IV., gives many similar cases of the forma- 

 tion of the cilia from the archoplasm (35, p. 62-13:^; 36, p. 184). Ihe 

 observations of Henking (17, 18), Flat iter l29', and above all oï von la 

 Valette St. George (13, 14', of the part played by the Nebenkern 

 in tlie formation uf the Spermatozoons are very interesting in this 

 (jonijcction, since the Isebenhern of these authors (especially of 

 voïi la IdU'tle St. (reimje) corresponds, as said above, in all particulars 

 with mv 'archoplasm "; and it is, therefore, very reasonable a priori to 

 consider that that part of the cytoplasm which is especially ditferen- 

 tialed for kinetic functions, is transformed to form a part of the tail of 

 a spei-matozoon or the flagellum of a Noc ti luca spore. 



C. Summa r g 



1) 'J'lie division of the animal is preceded by the loss of the 

 [icristome. teeth, and the tentacle, the last of which is not thrown oif, 

 as /('(*/*/// is inclined to think, but is withdrawn into the body of the 

 animal. The moutli and the Staborgaii arc. however, always present 

 (th>J>i,i). 



2) The spore-forming individuals differ from the dividing ones 

 in not possessing tlie mouth and the Slahorgan in addition to the 

 organs above mentioned, and by the excessively empty appearance of 

 the cell interior (Cienkoivskg). 



3) The division of the nucleus is always preceded by the con- 

 centration of part of the cytoplasm in the form of <*i spheri(*al or oval 

 granular bod}', mostly elose to the nucleus. This is the archoplasm 

 or the kinetic centre (of division, and corresponds most j)robablv with 

 the Sebeitkern of roit la I alette SI . (reorge. 



4) 111 living animals at the stage of (o), tbe nucleus appears more 



