LIFE-HISTORY OF ROTIFER 247 



In September, 1919, 100 individuals were chosen at random 

 from the mass cultures established in August, these being orig- 

 inally all descendants of a single individual. These were 

 reared under normal conditions until they had each deposited 

 three or more eggs. Three eggs from each of these 100 organisms 

 were used to start the experiment; one from each individual was 

 placed in a culture dish with 1 per cent alcohol in the solution 

 used in the bottom, another in a dish with 2 per cent alcohol, 

 and a third in a dish with tap-water to serve as a check for the 

 alcohol lines. The cultures were examined daily, the alcohol 

 solutions changed, and the adults transferred to fresh food. At 

 the end of the first week 100 organisms were isolated from each 

 main line and the length of life and the egg production deter- 

 mined in each. (See table 4 for a diagrammatic scheme of the 

 alcohol experiment.) At the end of the first week the range in 

 egg production for the 100 individuals from the 1 per cent alcohol 

 line w^as 1 to 7, with an average of 2.85, while the range in the 

 length of life was 2 to 6 days, with an average of 3.88 days; in the 

 line reared subjected to 2 per cent alcohol the range in egg pro- 

 duction was 1 to 6, with an average of 1.84; the range of indi- 

 vidual life was 2 to 5 days, with an average length of life of 4.19 

 days ; in the check line the egg production ranged from 6 to 30, 

 with an average of 20.86, while the range in the length of life was 

 3 to 5 days, with an average of 4.78 days. At the end of the 

 first week individuals from each of the alcohol lines showed a 

 decided reduction in the power to deposit eggs; those subjected 

 to 1 per cent alcohol depositing an average of 2.85 eggs, and 

 those subjected to 2 per cent an average of 1.84 eggs, as com- 

 pared with an average deposit of 20.86 eggs in individuals reared 

 under normal conditions. The average length of life did not 

 show as great a reduction; subjected to 1 per cent alcohol, the 

 individuals lived an average of 3.88 days; to 2 per cent, an average 

 of 4.19 days, while those under normal conditions had an average 

 length of life of 4.78 days. Thus there is a marked reduction in 

 the egg-laying capacity, unaccompanied by so great a reduction 

 in the average length of life, early in the history of a line reared 

 in alcohol. The viability of the eggs produced in these per- 



