ASCHKRSONIA ALEYRODIS. 15 



sterile water. The conidia were obtained from an old culture of the fungus 

 grown on sweet potato. All of the cultures, except two large petri dishes, 

 finally became contaminated with a growth of bacteria. This-was probably 

 due to insufficient sterilization of the interiors of the large masses of medium 

 : n the moist chambers and in the 500 cc. bottles. The fungus in the two 

 petri dishes which were successful, appeared in 15 days as a creamy white, 

 ieit-like growth over the surface of the medium, with no red color. Very 

 little red color appeared later, and no large spore-masses developed. It 

 seemed that the spores had been sown too thickly over the surface to develop 

 the characteristic pustules with pycnidial cavities. This experiment was 

 practically a failure. 



On June 12, 1907, five bottles of ground-up sweet potato, and one bottle 

 of bread, which had been sterilized in an autoclave for about half an hour 

 at 120 C., were inoculated by streaking the surface with a large platinum 

 loop from cultures previously made on sweet potatoes. Three of these 

 were successful, two on sweet potato, and one on bread. The notes on 

 these are as follows : 



1. On June 12, 1907, a culture on bread was made from a culture on 

 sweet potato plug, which had been transferred three times from an isolation 

 culture in petri dish poured December 7, 1906, and described above. 



Transfers had been made on January 14, 1907, April 10, 1907, and June 

 3, 1907. On June 19, the fungus was growing well at one point. 



On July 1, a large raised mass */2 inch in diameter was formed. On 

 July 20, a large area 1 inch in diameter, and red in the interior, with abund- 

 ant spores, had grown. 



2. On June 12, 1907, a culture on sweet potato was made from another 

 culture with same history as above. On June 19, the fungus had started at 

 seven points. On July 1, masses 1-3 inch in diameter had formed on one 

 side of the bottle. 



3. On June 12, 1907, a culture on sweet potato was made from a sweet 

 potato plug, which had been transferred once from a petri dish culture of 

 April 10, 1907, being transferred on June 3, 1907. On June 19, the fungus 

 was just starting at three points. On July 1, raised areas one inch in 

 diameter had formed on one side. On July 20, a growth l/ 2 inch in diam- 

 eter had formed. 



( )n June 19, six bottles of sweet potato and one of bread were inoculated 

 from sweet potato test-tube cultures which had been transferred twice from 

 an isolation culture made not later than April 10, 1907. Four bottles de- 

 veloped pure cultures. 



1. On June 19, 1907, the surface of a bottle of sweet potato medium 

 was streaked with a small needle from a culture of June 3, 1907. On July 

 1, three or four areas of growth had appeared. On July 20, a good white 

 growth had formed all around the base of the potato plug. 



2. On June 19, 1907, sweet potato medium was streaked as in No. 1, 

 from a culture made June 3, 1907. On July 1, a good growth had formed 

 on the surface, white and lumpy in appearance. On July 20, the growth had 

 formed all over the surface of potato, and spores had grown in the pycnidia. 

 On August 12, spores were very abundant. 



3. On June 19, 1907, sweet potato medium was inoculated by shaking 

 up conidia in a test-tube of water and pouring it over the plug. On July 1, 

 very small areas on side of glass appeared. On August 12, areas of large 

 size had grown, but no conidia could be found. 



