GROWTH 535 



Cutler and Crump (1923), using Colpidium, were unable to con- 

 firm Robertson; and Greenleaf (1924) failed to demonstrate allelocataly- 

 sis with Paramecium aurelia and P. caudatum, and with Pleurotricha 

 lanceolata. Peskett (1924) could not demonstrate allelocatalysis with 

 yeast. Robertson (1924) attributed their failures to the fact that they 

 had not washed their cultures free from the catalyst present in the me- 

 dium from which the cells were removed for inoculation. Cutler and 

 Crump (1925) and Peskett (1925) repeated their work, but were un- 

 able to demonstrate allelocatalysis either with washed or unwashed cul- 

 tures. 



Yocom (1928) found the division rate of Oxytricha higher in cul- 

 tures of four drops of medium than in ten-drop cultures, and attributed 

 the difference to an allelocatalyst. Petersen (1929) found that division 

 of P. caudatum was accelerated in volumes of culture of 0.83 ml., but 

 not in volumes of less than 0.21 ml. Dimitrowa (1932) obtained better 

 growth in "conditioned" medium which had previously supported the 

 growth of Paramecium than in medium which had not been "condi- 

 tioned." Colpidium campylum grew better when some sterile filtrate 

 from an old culture was added to a synthetic medium, according to Hall 

 and Loefer (1938). Garrod (1936) reported that small inocula of 

 Staphylococcus aureus did not grow in broth, but that large inoculations 

 would grow. Mast and Pace (1937, 1938b) give evidence in support of 

 an unknown substance produced in cultures, which, in low concentra- 

 tions, stimulates the growth of Chilomonas Paramecium, but which in 

 high concentrations retards the growth of the animals. A soil amoeba, 

 Mayorella, grown bacteria-free in mass cultures by Reich (1938), di- 

 vided less when the initial populations were small. His data, replotted 

 in the form of Figure 134, shows that the populations were proportionate 

 to the seeding in rate of growth, within the large errors of observation, 

 and do not support the allelocatalytic theory. 



Yeast populations grew at the same rate when the inoculation was 

 varied from 5 to 8 X 10'' cells per ml. (Clark, 1922); and from 12 to 

 1,200 cells per cu. mm. (Richards, 1932). Peskett (1927) found no 

 difference when one yeast cell was introduced into volumes from 0.008 

 to 40 cu. mm. Meyers (1927) failed to demonstrate allelocatalysis with 

 P. caudatum and found that conditioning the medium lessened the 

 growth of the animals. Increasing inoculations of Glaucoma up to 



