04 



S. E. A. McCallan 



TABLE 14. Percentage Germination of Sclerotinia Americana Conidia in Water 

 in Contact with Dialyzing Sacs of Varying Permeability Containing Colloidal 

 Bordeaux Membranes 



Discussion. The results of the first three experiments appear to clearly 

 substantiate the hypothesis of a solvent action on the part of the spore 

 execretions toward the insoluble copper compound. 



The results of the fourth experiment do not demonstrate this so clearly. 

 The figures in percentage columns 1 and 4 of table 14 show that the col- 

 lodion sacs were entire and did not leak. Hence, when they were standing 

 in pure water there was no appreciable outward diffusion of copper. 

 This would imply that no copper comes into solution merely on standing. 

 The results recorded in percentage column 3 show that all of the copper 

 which may have been brought into solution was absorbed, adsorbed, or 

 otherwise removed from solution by the spores, or possibly also by the 

 process of filtering. 



The figures in percentage column 2 show that collodion sacs of 20-80-2.5 

 formula are practically impervious to the inward diffusion of any solvent, or 

 the outward diffusion of copper, or both. The collodion sacs of 30-70-2.5 

 formula permitted a slight outward diffusion of copper, while the most 

 permeable sacs, 40 60-2.5, permitted a considerable outward diffusion 

 of copper. By a comparison with the three former experiments (table 13), 

 it would be expected that with the collodion sacs of greater porosity — 

 that is, 30-70-2.5 and 40-60-2.5 — sufficient copper would be allowed to 

 diffuse outward to completely inhibit germination of the spores. It is 

 beyond the scope of this paper to attempt to explain this difference in 



