SCIENTIFIC PROCEEDINGS. 



Abstracts of Commiuncations. 



Ninety-seventh meeting 



College of the City of New York, February 19, 191Q. 



President Gies in the chair. 



36 (1411) 



The effect of conjugation. 



By Gary N. Calkins. 



[From Columbia University, New York City.] 



A single individual (ex-conjugant) of Uroleptus mobilis was 

 isolated November 20, 191 7. Five lines of the series were main- 

 tained by the usual daily isolation culture method used with in- 

 fusoria. The relative metabolic activity is indicated by the aver- 

 age division rate of all five lines of the series for ten-day unit 

 periods extending throughout the life cycle. Once a week, the 

 excess individuals, after the isolations are made, are placed in 

 larger culture dishes for a conjugation test. Here they multiply 

 by division, until, in a week or ten days, thousands of individuals 

 are present. With increasing scarcity of food they will conjugate, 

 provided the protoplasm is sexually mature. From time to time, 

 ex-conjugants, obtained from such conjugation tests, are isolated 

 to form the beginnings of filial series. These are similarly main- 

 tained in daily isolation cultures, five lines to each series, and all 

 fed at the same times and on the same standardized culture medium 

 as the individuals of the parent series. This method furnishes 

 the possibility of comparing the vitality of a filial series with that 

 of the parent series. The protoplasm of 16 such series has been 

 studied, each series represented by five lines; seven series have 



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