Report on the Bacteriology of Water. 



433 



Cultures in Normal 10 per cent. Gelatine. 



Experiments on the effects of Temperature in the Dark, with constant 

 Food-material and conditions of Germination. 



In the following series I used throughout the same normal gelatine 

 10 per cent, gelatine, with broth and peptone and always incubated 

 the spores at 22 C. until germination was completed and the rodlets 

 in full growth. As far as possible, moreover, I started the growth- 

 measurements on filaments in exactly the same phase of growth, and 

 used drops of as nearly as possible the same size, and containing the 

 same number of spores, though it was found to be quite impracticable 

 to fulfil all these conditions absolutely. 



The arrangements Sachs' box, cells, temperature regulations, and 

 conditions of measurement were as before. 



I select a number of typical curves from a moch larger number, 

 and need only say that they are quite representative and fair examples. 

 The labour of recording the growths, working out the tables, and 

 drawing the curves has been very great, as will readily be understood ; 

 but it seems worth while to have done it to get the insights here 

 obtained into the marvellous regularity of growth that goes on when 

 the conditions are under control, quite apart from the other informa- 

 tion conveyed by the results. 



Still, it will be obvious that it has been impossible to carry out 

 more than one series so thoroughly in the time, and it must remain 

 for others to investigate the behaviour of the organism in other 

 media or under other conditions similarly controlled. 



On November 16 spores were sown in normal gelatine at 10 A.M., 

 and put at 22 C. till 6 P.M., and then put into the Sachs' box at 14 C., 

 and measurements made as follows : 



Curve 129, p. 434. 



Doubling period : 

 99198 M = 6.15 P.M. 9.27 P.M. = 192 minutes at 14 -2514 -513 '413 '9 C. 



