G. S.MITll 



243 



TABLE II. 



Dianieter of Tii(livi<luals in Microineter Units (unit of measurcment = l'Sl yu,). 



Table I. records the corrclation botween size of Actinosphdcrium and the uumber of cysts 

 built. The correlation coefficient =0-7692 +'0264. The Standard deviation of the sizes is 

 4-4372 Units =8-031 fi. ; that of the numbers of eysts is 2-9478. 



Table IL records the correlation between size of Actiiiosphaerium with number of nuclei. 

 Correlation coefficient =-8540 ±0168. The Standard deviation of the sizes is 3-4094 units 

 = 6-171 fi, that of the numbers of nuclei is 2-5181x50. The two correlation coefficients here 

 obtaincd are exceedingly high, as high as thoso we find between corresponding bones of two 

 fingers of the same band, etc. It would be iuterestiug to see whether equally high coefficients 

 obtain for uiultinucleatc Proto:oa in general. 



The above correlation tables had shown that great variability existed in 

 Äctinosphaeria of similar bulii as to the number of nuclei they contained and as 

 to the number of cysts they built during encystment, and that these two variables 

 corresponded in a certain degree. In the course of couuting and observing the 

 cysts tabulated in Fig. B. I became gradnally impressed with a further fact, 

 namely, that the cysts built by different individuals were often of very ditfcrent 

 sizes, and moreover that the size of the cyst seemed to bear a certain relation to 

 their number: i.e. wlien an Actinosphaerium had built very numerous cysts for 

 its size thcn those cysts were generaJly small, aud vice versa. On Plate I. 

 Fig.s. 1a — 1.5 are collected the most striking e.xamples of this fact, which I could 

 gather from these first experiments. Here it will be .seen that in Actinosphaena 

 of all kinds of sizes individuals occurred, some of which built numerous and small 

 cysts, while others built fewer and larger. 



The uext preliminary experiments were directed towards Unding out what 

 efifect would be produced on the number and size of the cysts by subjecting the 

 animals to different temperatures. Animals of a certain size (3G-2 — 39-8 /u.) were 

 selected : half were placed in an incubator at 24° — 26° C, the other half were 

 placed in au unheated room where the temj^erature varied between 7° and 12° C. 



31—2 



