Endomixis in Diverse Races of Paramecium aurelia. 161 



amplitude of the individual contractions increased markedly under 

 cooling and diminished under heating. The other four experi- 

 ments were negative. 



Thus far then we have established a definite cerebral in- 

 fluence over the volume of the uterine cavity. The fact that this 

 appears to be largely if not entirely a control of the voluntary 

 musculature of the abdomen does not detract from its importance 

 in connection with the birth process. 



Returning to the morphin question, we have now given small 

 subcutaneous doses of this substance in two animals which had 

 responded well to cerebral cooling and heating in the manner 

 above described. Here the morphin, given to unanesthetized 

 animals, resulted in a depression of the uterine activity, although 

 the dose was so small in one case (.01 gram per kilo) that 

 the animal remained sitting upright and occasional normal limb 

 movements continued to occur. Cerebral cooling now had no 

 effect upon the volume of the uterine cavity of these morphinized 

 animals, showing clearly how morphin can influence labor by a 

 central action. 



89 ("S3) 



Endomixis in diverse races of Paramaecium aurelia. 

 By Lorande Loss Woodruff. 



[From the Osborn Zoological Laboratory, Yale University.] 



Woodruff and Erdmann in 1914 1 described a normal periodic 

 reorganization process without cell fusion, which they termed 

 endomixis, in Paramaecium aurelia. This study was based chiefly 

 on pedigreed cells from Woodruff's 5,000-generation race of Para- 

 maecium aurelia, though specimens of a race of this organism 

 isolated by Erdmann in Germany showed the same phenomenon. 



The present communication is to prove the general occurrence 

 of endomixis in races of Paramaecium aurelia, since this has been 

 questioned, on a priori grounds, by certain authors. 



The following races of Paramaecium aurelia, in addition to 

 those mentioned above, have now been studied: 



Oberlin Race. Isolated at Oberlin, Ohio. Carried in pedi- 



1 hoc. cit. 



