368 Journal of Agricultural Research voi. v, no. 9 



Kock (1910) ascribes the resistance of certain varieties of cherries to a 

 blossom-blight caused by 5. cinerea to the blossoming of these varieties 

 when conditions are unfavorable for the disease. 



Cook and Taubenhaus (191 1 and 191 2) pointed out the toxic proper- 

 ties of tannins and fruit acids and also showed a relationship to exist 

 between the decrease in oxidizing enzym content of fruits and the 

 increase in their susceptibility to disease. 



With regard to the physiological relationship between host and para- 

 site, considerable work has been done. Jones (1910) gave a compre- 

 hensive review of the literature on this subject, dealing especially with 

 the bacteria. Cooley (191 4) reviewed much of the work on the physio- 

 logical relations of the fungi. Therefore, only a short review will be 

 given of the literature dealing with Sderotinia spp. 



Behrens (1898) in his work on the physiology of Oidium {Sderotinia) 

 friictigenum, Penicillium spp., and some other fungi, concluded that 

 5. frtictigenum was exclusively an intercellular fungus and did not 

 secrete a cellulose-dissolving enzym. He considered that the fungus 

 split the middle lamella by mechanical force. Penicillium spp., he con- 

 cluded, also did not enter the cells, but did produce a middle-lamella- 

 splitting enzym. 



Schellenberg (1908) studied the effect of 5. frtictigena and 5. cinerea 

 on a number of tissues, but not on their respective hosts. He considered 

 both of these fungi to be intercellular, producing no cellulose-splitting 

 enzym. He thought, however, that they did produce a hemicellulose- 

 dissolving enzym and that the cell walls in contact with the hyphge were 

 sUghtly dissolved. He saw no evidences of a middle-lamella-splitting 

 enzym. 



Bruschi (191 2) noticed, whenM. cinerea was grown in a medium con- 

 taining plum flesh, that after 48 hours the cells were all separated from 

 one another, and concluded that the fungus produced the middle-lamella- 

 splitting enzym pectinase. Attempts to isolate a cellulose-dissolving 

 enzym were unsuccessful. 



Cooley (191 4) demonstrated the ability of 5. cinerea to produce an 

 enzym which would coagulate pectin from solution in the absence of 

 calcium. This enzym he called "pectinase." His use of this term is, 

 however, not clear, as he states (p. 314) that he adopted "the nomencla- 

 ture used by Jones and Euler, namely, employing pectinase as the term 

 to designate the enzyme inducing coagulation of a pectin solution and 

 also the hydrolysis of calcium pectate, or pectinate." Jones (1910) used, 

 in a general way, the nomenclature suggested by Bourquelot and Heris- 

 sey (1898) regarding the enzym which they extracted from barley malt; 

 as he says (p. 355), "All things considered, we favor the name pectinase, 

 which was suggested by Bourquelot and Herissey, as already explained." 

 On the other hand, Euler-Chelpin (191 2, p. 32) states that "The enzyme 



