I 9 2 BOTANICAL GAZETTE [march 



yet such an explanation is improbable when we remember that other 

 compounds easily derived from alcohol, e. g., acetic acid, ethyl acetate, 

 and potassium acetate, furnish material for the development of the 

 fungus and the production of spores. It is also possible that the 

 suppression of spores is due to some deleterious action of the alcohol 

 in the culture fluid, although it is difficult to see how a substance can 

 at one and the same time act as a food of high nutrient value and as a 

 poison. At first sight the cultures containing both ethyl acetate and 

 alcohol would seem to bear out the view that alcohol was deleterious 

 to spore-formation, for cultures with ethyl acetate alone fruited, while 

 those containing alcohol also failed to fruit. In such cultures, how- 

 ever, it is probable that the more nutritious alcohol was absorbed 

 first, and largely to the exclusion of the acetate. Further work is 

 necessary to give a complete explanation of this unusual phenomenon. 

 It may be found that all strains of Penicillium do not act alike in this 

 respect. 



Another fact, brought out in the course of this investigation, was 

 the great individual difference of resistance of spores to deleterious 

 agents. In the lower concentrations of all substances favorable for 

 growth, practically all spores germinated, forming a dense matlike 

 growth over the surface of the culture fluid. When, with increase of 

 concentration, the substance becomes deleterious, germination and 

 growth are not stopped abruptly, but the number of colonies becomes 

 fewer and fewer until the final concentration is reached, where germi- 

 nation of even the most resistant spores is inhibited. In most cases, 

 where only a few colonies were formed, these grew with unusual vigor, 

 so that the total weight of the culture was often as great as that of the 

 cultures of lower concentrations. 



This was especially well shown in the series with potassium acetate, 

 tables XIII-XV. Here comparatively few spores germinated in the 

 higher concentrations, forming isolated floating colonies. Yet the 

 yield from these was equal to the yield from other flasks which were 

 uniformly covered. This seems to indicate that the mycelium from 

 the more resistant spores continues itself to be more vigorous through- 

 out life, although it is not impossible that the belief of Duclaux holds 

 true here; that is, while the concentration in any given case may be 

 injurious to germination, it does not interfere with later development. 



