juneio, 1918 Experiments with Coccomyces spp. from Stone Fruits 541 



draped with cheesecloth, which throughout all clear days of operation 

 was kept continuously moist by small streamlets of water from pipes 

 which were conveniently attached to the ridges of the slanting roofs. 

 The evaporation from the cheesecloth, even on the hottest days, kept 

 the temperatures within the chambers below 32° C, while the excess of 

 water kept the soil under them saturated. During the day the tem- 

 peratures ordinarily ranged between 20° and 28° C, and the relative 

 humidities between 90 and 100 per cent. At night the temperatures 

 were generally lower, while the humidities usually reached or closely 

 approximated saturation. While these chambers gave good results, 

 their weight proved to be a serious practical disadvantage, and in 191 7 

 they were replaced by the much more convenient apparatus described 

 on page 546. 



The inocula were applied by means of atomizers, the construction 

 of which was satisfactory and particularly well adapted to steam 

 sterilization. 



Inocula. — When the inocula were procured from cultures, spore sus- 

 pensions were prepared by introducing sterile distilled water into the 

 culture tubes and teasing the spores into suspension. Such suspensions, 

 suitably diluted with sterile distilled water, comprised the inocula. All 

 cultures used were from single-spore strains. For direct inoculations, 

 spore suspensions were prepared by removing the contents of acervuli by 

 means of sterile scalpels to sterile distilled water, in which they were 

 stirred and suitably diluted. 



Just before the inoculations were made, drops of the suspensions to 

 be used were placed on clean sterile glass slides in moist chambers and 

 tested for viability of spores. 



METHOD OF INOCULATION. — The inoculations were always made late 

 in the afternoon. The moist chambers already described were placed 

 over the experimental plants and the ground inside was abundantly 

 watered. The inoculum was then applied as spray by means of the 

 sterile atomizers. The chambers were promptly closed and were kept 

 continually wet on the outside by means of the devices already described. 

 Unless otherwise stated, they were always left in place for two days. 



Of the controls, series i was treated in every way like the inoculated 

 plots, except that sterile distilled water was used instead of an inoculum. 

 The additional special controls, which were located near each plot in the 

 manner already described (p. 540), were left untreated. 



RESULTS OF EXPERIMENTS OF 1916 



A summary of the experiments of 191 6 appears in Table I. 



Of the 30 control plants, which included all the experimental species 

 and varieties except P. padus, which died, only one, P. avium, had 

 developed any infection when the final notes were made on October 14. 



