Jul,- i9iM AUXOSPORE- FOR RATIOS OF CJTAETOL'ERAS DER1LE. 149 



lateral side, the former shows also its lateral side to the 

 observer. 



When two auxospores are formed pairwise, the chromo- 

 plasts in them are found in the remotest positions from each 

 other. (Fig. 5.). The directions of the curves of the daughter- 

 chains are thus alread\ r indicated. The chromoplasts of the 

 present species, as alluded to above, are single in each frustule 

 and are located in the inner side of the chain-curve. The two 

 chains from the pairwise auxospores, therefore, diverge gradual- 

 ly as the chains elongate. The directions of the setae of- 

 course answer to chain-curve. 



Sapporo. 17, May, 1918. 



Explanation of Plate. 



Fig. 1. A part of chain with two frustules just before the spore-formation. 



Fig. 2. The two frustules are perforated ; the cell-contents bulging out through the 

 holes. 



Fig. 3. A spore-forming frustule has discharged a greater portion of the content. 



Fig. 4. Beginning of the formation of a daughter-chain 1 the first frustule of the 

 chain seen from a narrow end, a seta has appeared at the center as a short prick. 

 The perizonium is still keeping its original shape. 



Fig. 5 Two auxospores from the adjoining frustules : the first frustules of the 

 daughter-chains half-completed , the perizonia are much stretched as to follow the 

 growth of the frustules, the setae pierced out through the perizonia, and the 

 chromoplasts t iking remotest positions from each other. 



I ;.'. 0. The first-formed frustule of a daughter-chain divided into two: the 

 ppitheca of the first frustule still remaining in the ruptured perizoniam. The axis 

 of tli danghter-chaiu lies at right angles with 'that of the mother-chain. 



Fig. 7. A ruptured perizonium free from the daughter-chain but still attached 

 to the molher-frustule. 



I - A danghter-chain with eight frustules still attached to th<- mother- 

 chain. The epithecae of the end frustules are markedly Bwollen in the middle. 

 (Fig. 7.X820, all the others,x670). 



a in 1 1 : (Yii.-r Vuzosporenbildung dei Qattnng Cftaetooera*, Taf. XIV. fig. 9. 



