On the Formation of Auxospores and 

 Resting Spores of Chaetoceras 

 teres, CLEVE. 



By 

 Jiro Ikari. 



With Plate V and Text-figures. 



The auxospore-formation of diatoms has hitherto been observed 

 in about 70 species of different genera, and witli regard to it, four 

 types arc distinguished by Karsten.^^ In Chaetoceras, one auxospore 

 is formed in one mother cell, that is the mode belonging to the fourth 

 type of Karsten, called by him as " Ungeschlechtliche Auxosporen- 

 bildung." The auxospore-formation of Chaetoceras has been observed 

 by SciiiiTT,- Gran^ and others. The present writer''^ in joint-work 

 with the late Prof. K. Yendo has also studied it in Chaetoceras 

 dehile, Cleve. 



In April, 1920, I had a very good opportunity of studying the 

 auxospore-formation of Chaetoceras teres and several other species at 

 the Marine Laboratory at Oshoro in Hokkaido. Gran reports that 

 he has also observed it in sevei-al species, Ch. constrictum, Ch. 

 diadema, Ch. dehile, and Ch. teres and remarks that it takes place 

 in these species in the same way as in Chaetoceras curvisetum. So 

 it may not be necessary to make any description in regard with the 



1) Karsten: Die Diatomeen der Kieler Bucht. 1899. p. 168. 



2) after Schutt in Engl. u. Peantl : Pflanzenfamilien. T. Theil. lb. 



3) Gran: Den Norske Nordhavs-Expedition. 1876-1878. 



Botanik Protophyta. p. 8. 



4) Yendo & Ikari : Auxospore-formation of Ck. debile, Cleve. Bot. Mag. 

 Tokyo. Vol. XXXII, No. 379. 1918. 



