(.)84 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The method for calculatiug was as follows : — 



Lot a = uumbcr of primary colonies. 

 b = „ secondary colonies, 



n = „ generations. 



a cells or rods after 1 generation = a x 2. 

 2 generations = a X 2 X 2. 

 n „ = a X 2". 



.-. a X 2" = b. 



2- A. 

 a 



log, - log. . 



n = z • 



logs 



The cholera vibrio was chiefly experimented on, and the results of 

 seven examinations are given. In number these are too few for any 

 precise knowledge ; in certain details of time they vary considerably, and 

 the last experiment given was apparently the fii'st made, and seems to 

 have been thrown in to add length to a too short series. 



The following are the numbers given : — 



Experiment 1. (Feb. 1887.) Duration 3 hours. 



Primary colonies = 18 



Secondary „ = 7250 



n = 8-7 



.', each brood developed in 20*7 minutes. 



Experiment 2. (Feb. 1887.) Duration 3 hours. 

 Primary colonies = 149 

 Secondary „ = 95,952 

 n = 9-3 

 Period of development = 9*3 minutes. 



Experiment 3. (Feb. 1887.) Duration 2 hours. 

 Primary colonies = 3,583 

 Secondary „ = 90,666 

 n = 4-7 

 Period of development = 25 • 5 minutes. 



Experiment 4. (March 1887.) Duration 2 hours. 

 Primary colonies = 15,345 

 Secondary „ = 133,545 

 n = 3-1 

 Period of development = 38 ■ 7 minutes. 



Experiment 5. (March 1887.) Duration 2 hours. 

 Primary colonics = 3,550 

 Secondary „ = 27,608 

 ?i = 3 

 Period of development = 40 minutes. 

 Experiment 6. (April 1887.) Duration 2 hours. 

 Primary colonies = 143 

 Secondary „ =1291 

 n = 3-18 

 Period of development = 37'7 minutes. 



