Effects of Alcohol on Paramecium 195 



lines was started in a ^ per cent alcohol infusion. This alcohol 

 medium was increased by | of I per cent each day. The culture 

 died when transferred into 9 per cent solution. 



Separate pipets were kept for each culture and great care was 

 taken to transfer as little infusion as possible along with each indi- 

 vidual. A lens having a magnification of ten diameters was used 

 entirely in transferring specimens with the pipet from one slide to 

 another. This was easier than using a compound microscope. 



The slides were kept in moist chambers to prevent evaporation 

 of the infusion. These were stender dishes nine inches in diameter 

 and three inches deep. In the bottom there was moist sand one 

 inch deep on which rested four glass rods and on these rods were 

 placed the depression slides. Then over all was placed the tight 

 fitting cover. Cover glasses were not used on the depression slides. 

 Each day the rate of division was recorded for each of the cul- 

 tures. When the count was made, an individual from each line 

 was isolated on a clean depression slide in four drops of the culture 

 medium. The four lines in each culture were averaged to get the 

 daily rate of division, and this result was again averaged for eight 

 day periods. In this way, fluctuations in division rate are elim- 

 inated and we have a more reliable and comprehensive result than 

 would be obtained by carrying a single line. 



The rate of division was taken as the index of the physiological 

 condition of the organisms. All previous investigators in this 

 field have considered this to be the most accurate indication which 

 is available. 



Believing that more reliable data could be had if the alcohol was 

 mixed directly with the culture medium in the desired proportion, 

 this plan was followed entirely. This method eliminates a pos- 

 sible source of error found in the "dropping" process which has 

 been used extensively in similar experiments. 



A COMPARISON OF HAY INFUSION AND ALFALFA INFUSION AS 



CULTURE-MEDIA 



On January 6 the six cultures were started in ordinary hay infu- 

 sion. From the first, the rate of division was low and it was plain 



