24G 



A et in osphaeriu m Eich ond 



killed, stiiiued und tlicir uuclei Cüuutcd. Fig. A. The othcr part was put to 

 encyst at room teniperature 15° — 19° C. with the result shown in Fig. B. Froin 

 theso figures the proportion of nuclei retained for encystnicut at room temporature 

 by individiials of the abovc size can be fairly accuiately gauged. The nuinber is 

 somowhat lower thau previous observers have found ; but it will be showu that 

 the nuinber of nuclei retained is greatly dependent on teniperature. 



C. When an Aciinonphaerium builds few cysts for its size then tlie cysts tend 

 to be sinall, and vice versa. 



If reference be made to Table 111. uhich lefer.s to the cysts built at room 

 temperaturc, a complete confirmation of tliis rulu will be obtained. This table 

 was made up from tho.se individuals used for constructing Fig. B whose cysts 

 couKl be conveniently mea.sured : the measurements rcfer to the diameter of the 

 conjiigation cysts. This table expresses the correlation between the nuinber of 

 cysts and the size of the cysts. The correlation coefficient = — 06689 + '0402. 

 The Standard deviation of the numbers of cysts = 1'7599 ; that of the sizes 

 of the cysts = 2"34'87 x S/i,. It will be seen that we have a most substautial 

 negative correlation. 



TABLE III. 



Number of Cysts at 15" — 19° C. 



ü 



c 

 o 



3S 



o 

 O 



Since the cysts built by onc and the same individual are not always of exactly 

 the same size I have had to avcrage the size of the cysts in each individu.U. 

 This applies to the wholc table. Tiio diffcrence in size of the cysts built b}- -Mxy 

 one individual was frequently nothing and only in two or three cases more thaa 



