juneio, i9i8 Experiments with Coccomyces spp. from Stone Fruits 549 



While, in order to avoid excessively high temperatures, it was necessary 

 to screen this chamber against direct sunlight, the experimental plants 

 received a good supply of diffuse light. This apparatus gave very 

 satisfactory results, maintaining a humidity which closely approximated 

 saturation. 



All spore suspensions were applied by atomizers, as in the outdoor 

 series (p. 547). 



In making inoculations with ascospores, application of the spores by 

 means of natural discharge of the asci was by far the most satisfactory 

 method tried. This was accomplished by adaptation of methods which 

 have been used by 

 others.^ The simple de- 

 vice used is illustrated 

 in figure 3. The wash- 

 ers were cut from gasket 

 rubber by means of cork 

 borers, which were also 

 used for cutting the 

 ascogenous leaf frag- 

 ments. The cover 

 glasses were standard 

 No. 2 squares (22 mm.). 

 The clips were made 

 from No. 24 brass wire, 

 and furnished a grip 

 which, while adequate 

 for holding the appa- 

 ratus in place, was not 

 strong enough to injure 

 the leaves. These de- 

 vices gave very satisf ac- 

 toryresults(P1.59,C,D). 



Inocula. — Unless otherwise noted, all inocula were prepared like those 

 of the outdoor experiments (p. 546). 



Method of inoculation. — In all series inoculated with spore suspen- 

 sions the experimental plants were removed to the pathologium,^ where 

 they were sprayed in the same manner as the outdoor series (p. 547) and 

 placed in the moist chamber. Similarly, in the inoculations by discharge 

 of asci, the experiments were set up in the pathologium, and the plants 

 were then promptly placed in the moist compartment. The inoculations 

 were made on the lower (dorsal) surfaces of the leaves, which were left in 

 such position that the spores might be discharged downward upon them 

 rather than upward. This was easily accompHshed after the plants had 



1 Particularly helpful suggestions in this regard were kindly given by Dr. F. R. Jones, now Pathologist, 

 Cotton, Truck, and Forage Crop Disease Investigations, Bureau of Plant Industry, United States Depart- 

 ment of Agriculture, and by Prof. James Johnson, of the University of Wisconsin. 



2 Pathologium: A phytopathological laboratory used in conjunction with a greenhouse. 



Fig. 3. — Device used for inoculation by means of natural ejection of 

 ascospores: A,oaP. americjna: B, in cross section (see text), a, cover 

 glass; b. rubber washer; c, ascogenous leaf fragment; d, leaf to be 

 inoculated; ?, clip. 



