G. Smitii 245 



In 60 hours tlio individual.s ot' tlie wann ciiltiire were already in the conjugation- 

 cyst stagc, while the similar coli! cultiirc was not in a sinüiar sta^e of cncystniciit 

 tili a week and four days after it was prepared. Thf two cultuixs l)uilt cysts in 

 the following numbers : — 



No. of cysts 2 8 4. 



Frequenoy in wann cnltiire 2 4 6 

 Freqnency in cold culture Ü 1 



The reason wliy fewer reached tho conjugation cyst stage in the cold culturo 

 was that owing to the delayed encystnient the cultui'e had to be morc frequentiy 

 weeded of individuals that had divided etc. This experiment suggested that the 

 higher temperature caused fewer cysts, and the cold caused more nnnicrous cysls 

 to be built, while on Plate I. Figs. 16 — 22 show that the rule adinnbratod by the 

 previous experiment is confirnied by these, since the cysts fonned in the cold 

 being more numerous are at the same time smaller than the comparatively few 

 cysts built in the warm. 



The preliminary experiments now described had suggested the following facts 

 and Problems : 



A. An Actinosphaeriuni of a given size may contain a number of nuclei 

 varying between wide extremes and in consequence — 



B. It may build a varying number of cysts. 



C. When it builds few cysts for its size then the cysts tend to be large ; 

 when it builds many they tend to be small. 



D. An increased temperature hastens on encystment, a low temperature 

 retards it. 



E. An increased temperature causes fewer and larger cysts to be built, 

 a lov/ temperature causes many and smaller, i.e. an increased temperature causes a 

 greater percentage of nuclei to be thrown away. 



F. In what way does the temperature act upon the number of nuclei 

 rejected ? That is, does the temperature affect the number of nuclei gradually, or 

 only at the period when they are being rejected ? 



G. In what way does the size of the cyst affect the nucleus contained ? That 

 is, does the nucleus vary in correspondence to the varying size of the cyst or does 

 it remain the same so that a different mass-relation between nucleus and cyto- 

 plasm occurs in the different cases ? 



Further Researches. 



The following researches were directed towards confirming, correcting and 

 answering the facts and queries lettered above. 



A and B. To test these observations more narrowly several hundred in- 

 dividuals were selected of a certain size (34-39 — 4103 fi). A part of these were 



