J. Henderson Smith 



29 



cases where it was impossible to complete the counts quickly enough, 

 a few drops of chloroform were added to the cell after incubation. This 

 arrested all further growth and the slides could be counted at leisure. 

 Some device of this sort was necessary, because otherwise the hyphal 

 growth becomes so profuse as to make accurate counting impossible. 



The dilution of the sample in the centrifuge tube arrests the action 

 of the phenol by lowering its concentration to a point much below that 

 which has any perceptible effect on the spores in the time given. The 

 number of spores contained in the final mixtures was determined by 

 direct counting in the Thoma-Zeiss haemocytometer. 



In Table I is given the result of an experiment with 0-4 per cent, 

 phenol and spores taken from the tube 27 days after inoculation. During 

 the first 20 minutes apparently none of the spores are killed, but in the 

 second 20 minutes about 1-5 per cent, die, and in the third 20 minutes 

 a further 7-5 per cent., in each successive interval more and more dying 



Table I. Expt. of 23. 10. 19. Spores 27 days old; 150,000 per 1 c.c. 

 Phenol 0-4 per cent. Temp. 25°. 



