146 TBE BOTANICAL MAGAZINE. LVoi. xxxn. no. 379. 



spore-forming individuals were immense in number. We could 

 trace all the stages of the formation at living material. The 

 result we have obtained are affirmative of Schutt's observation 

 in the essential points. Still we trust a brief description of 

 what we have observed will not be uninteresting to the 

 Diatomists. 



Chaetoceras debile Cleve is to be found whole year round 

 in the vicinity of Oshoro. Its utmost luxuriancy there about 

 is during October— April. In March — April, the chains of the 

 species have frequently the resting spores in them. It was 

 also the case in this year, but to meet with such a considerable 

 number of the frustules simultaneously busy for the auxospore- 

 formation, it was quite unusual. 



The chains of frustules which will have the auxospores in 

 them have no marked morphological difference from the or- 

 dinary ones, except much smaller diameter of the frustules. 

 The frustules found in other seasons of the year vary in their 

 breadth from 12// to 30//, while those in the said season there 

 is a very little fluctuation in their sizes, measuring 15—18// in 

 breadth and 9-12// in height. The frustules which directly 

 concern with the spore-formation, however, are markedly taller 

 than any sister-frustules in the same chain and measure as tall 

 as 22-30//. 



The auxospore-formation of Chaetoceras debile Cleve we 

 have observed is carried out by single frustule, i. e , it belongs 

 to the "Auxospores asexuelles, type 1." of Mereschkowsky. 

 It is rather exceptional to find only one auxospore in a chain. 

 In most cases two auxospores are found pairwise, each formed 

 by one of the adjoining two frustules. Very frequently, two 

 pair of auxospores in a chain are also met with. There is no 

 doubt that the pair have been originated from the same 

 mother-frustules and hence both of each pair are same-aged 

 and have the same physiological characters. The pairwise oc- 

 currence of the resting spores in one chain many be explained 

 as to have similar significance. 



The tall frustule read}' for the spore-formation is rich in a 

 highly refracting, granular substance. The granules aggregate 



