studies of Reproductive Elements. 



II. Noctiluca miliaris, Sur. ; its Division 

 and Spore-formation.'"' 



By 



C. Ishikawa, Ph. D., Rigakushi, Rigakufiakushi. 



Pi-ofessoi- of Zoology, Agiicnltnral College, Imperial University. 



With Plates XI-XIV. 



A. DESCRIPTIVE PART. 



a. Division. 



The individuals of the nenn« jSToctilncn which are preparing to 

 divide can easily be distinguished from the others by their spherical 

 form, caused by the absenœ of tlie peristome and of teeth, and by the 

 diminislied size of the tenta<"le (Figs. 1 and 2) ; but the Stahorgan is 

 always to be seen as a narrow line of cytoplasm, extending backwards 

 from the nucleus and marking the line of division. The tentacle ap- 

 pears to be drawn into the body of the animal, as Cienkoivski/ (6, 

 p. 50) first observed, and not thrown off, as Robin ( 6, p. 1064) is 



* The materials upon which the following* observations Avere carried out were in part collect- 

 ed by myself from different parts of the sea coast near Tokyo, for instance, in Numadsu, Zushi, 

 Tateyama-in-Boshiu, etc, and in part from the Misaki Marine Biolo<,àcal Station of the Science 

 College of the University, where I worked for a fortnij^ht during- the summer of 1890, for a 

 week during- the winter of 1892-93 and again for a week at the end of August this year. For 

 all these opportunities and for the free use of the library of the Zoological Laboratory of the 

 Science College, I express my warmest thanks to the authorities of the College, and especially 

 to Professor Mitsukuri. 



