G. Smith 



TABLE IV. 



Numbrr i.r ('vsis. 



249 



Arabic figures refer to Individuais encysted at 24° — 20° C, Arabio figures in brackets to individuals 

 encysted at T' — 12° C, Roman letters to individuals starved in the oold and introducod into the 

 warm. 



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

 rejected ? 



It i.s piain that the temperature niay act in one of two way.s ; either it may 

 gradually increase or decrease the number of nuclei before ency.stment sets in, or 

 eise it may have no effect duriug this period but only at the actual onset of 

 encystment, when the nuclei are being rejected. That this latter alternative 

 is the truth is shown by the following e.xperiments. 



1. A culturc was put to starve in the cold (7" — 12' C.) on Nov. 23rd. It 

 was introduced iuto the warm temperature (24° — 26 " C.) on Dec. 2nd, none of 

 the creatures having as yet liegun to encyst. On Dec. 8th conjugation cysts had 

 been formed by all the individuals. The result is shown in Table IV. by the 

 Roman letters. Here we see that whatever effect the application of cold uuder 

 starvation for nine days may have had is obliterated by the subsequent applica- 

 tion of warmth, for the Roman letters fall indifferently among the Arabic which 

 refer to ordinary warm encystments. 



2. Individuals of various sizes were well fed with Stentor in the cold. 

 Half of them were killed and stained and found to be very rieh in nuclei. The 

 other half were introduced into the warmth on Dec. 7. On the following day they 



Biometrika ii 32 



