252 



ANIMAL AGGREGATIONS 



of the inoculum. In these yeast cultures of Montank's, when the 

 logarithmic growth stage is reached, growth is more rapid the smaller 

 the seeding, except with the smallest amount used, where the rate of 

 increase is distinctly less than with the next higher amount. This 

 is in line with Robertson's findings for the effect of the size of the 

 seeding upon rate of reproduction in certain protozoans in which 



TABLE XXVIII 



Showing Montank's Data on the Influence of Size of Seeding upon 



THE Growth Curve in Yeast 



(Figures Are Given in Terms of Millions of Cells per 



Cubic Centimeter of Medium) 



Hours of Incubation 



Flask No. 



■4... 



6.., 

 8.., 

 10. 

 12. 

 16. 

 20. 

 24. 

 36. 

 48. 

 72. 

 96. 

 144 



20.9 



23.8 



37.8 



58.9 



105 5 



129.0 



161. 6 



174-7 

 176. 2 



181. 

 183.6 

 186.0 



185. 1 

 1950 

 197.9 



O. 2 

 O. 2 

 O. 2 



03 

 I .0 



3.8 



II. 8 

 44.8 

 89.3 

 1237 

 138.3 

 146.7 

 162. 2 

 176.3 

 180.3 



0.02 

 0.02 

 0.025 

 0.02 

 0.02 

 0.024 

 0.04 

 o. 26 

 30 

 18.3 



114. 6 



1350 



160.0 



165. 2 



175.8 



0.002 

 0.002 

 0.003 

 0.003 

 0.004 

 0.004 

 0.005 

 0.005 

 0.006 

 0.007 

 o. 289 

 1 .089 

 93.264 

 169.400 

 171. 408 



the rate of reproduction at early stages of the subcultures was more 

 than doubled by seeding with two rather than with one organism. 

 It may be remembered that Peskett (1924, 1925) using isolation 

 cultures failed to find increased growth-rate with increased number 

 of cells present at any number level tested. 



The experience with bacterial cultures parallels experience with 

 protoz-oan and other animal cultures in another respect, in that the 

 final yield is practically independent of the seeding as long as the 

 seedings are smaller than the normal maximum yield of the medium. 



MASS PROTECTION FOR BACTERIA 



The evidence for mass protection for bacteria to be presented 

 here is based almost entirely upon the studies of Churchman and 



