EECENT RESEARCnES ON THE RADIOLARIA. 



105 



of aggregated nuclei only. As regards the less subdivided masses, 

 each such mass consists of nuclei with sarcode aggregated round 

 each nucleus. Fig. 13. 



Heaps of nuclei forming masses with different degrees of subdivision in Collo- 

 zoum incrme. A. Mass consisting of nuclei only. B. Mass consisting of 

 nuclei each with a sarcodic envelope. (After Hertwig.) 



The masses which thus exist in two states of subdivision have 

 different destinations, or rather different products, respectively. 

 The oil-globules have now disappeared, but instead fat-granules 

 have appeared in the middle of each nucleus. 



At this stage the whole colony sinks and the alveoli disappear, 

 just as is the case at a corresponding stage of the development of 

 those forms of Collozoum which are provided with crystals. The 

 next change is for each heap of nuclei to break up, and each part 

 (nucleus, or nucleus and sarcode) becomes a zoospore ; but, strange 

 to say, the zoospores are of two kinds, macrospores and microspores. 



The aggregations above described as consisting of smaller parts 

 (formed of nuclei only) give rise to the microspores ; the macro- 

 spores are formed from the less divided masses (formed of nuclei 

 with sarcode round each nucleus). The products bear no relation to 

 the size of the aggregations themselves, but to the size of their 

 component parts. 



Each zoospore consists of a bean-shaped 

 body, with a long flagellum extending from 

 that end of the body where a nucleus can be 

 made plain by osmic acid. Towards the other 

 end of the body there are fat-granules, but 

 there is no crystal. The macrospores are 

 constantly twice the size of the microspores. 



As to the meaning of the difference of 



spores, Hertwig supposes, naturally enough, 



that it is related to some difference of function. A. Two microspores 



As to the difference in manner of repro- and R Two macrospores 



or (JoUozoum merme. 

 duction with respect to the presence or ab- (After Hertwig.) 



