REPORT OF THH SOCIETY 65 



of a petiole attacked and half way in the case of a stem. It was noticed that the 

 majority of the lesions were near the nodes or where the cotyledons had dropped 

 ofiF. The lesions elsewhere had a slightly different shape and were often quite 

 sharply pointed at the upper and lower extremities. 



On the pods. 



Here as it has already been mentioned the lesions are very small and seldom 

 developed over 1 mm. in diameter. These lesions were very dark in color. The 

 centre was nearly black with a reddish margin. The developing bean pods 

 were injured apparently bj^ the readiness with which the organism attacked the 

 remains of the sepals around the stem and causing a lesion that frequently 

 involves the peduncle so that the food supply appeared to be cut off. That this 

 was so could not be definitely determined. The beans certainly did not reach a 

 normal size but it was impossible to say how great an influence the greenhouse 

 conditions had on the plant. 



Morphology of the organism. 



The spores in a fresh culture are ovoid-cylindrical, straight or very slightly 

 curved and hyaline. Under lower power magnification, many appear as two 

 gullulate with some having as high as three or four guttules. Ellis described 

 Phoma suhcircmata as being two-nucleate. 



The spores ranged on potato dextrose agar from 9.3 to 3.8 to 4.6 x 1.7 

 microns and averaged 6.48 x 2.62. Saccardo's were 6 x 2.5 and Smith gave 

 them as 4-6 x 2-2.5. Ellis and Everhart report Phoma suhcircinata as teing 

 5-6 X 2-2.5 but Harter in making a study of the type material states that he 

 found the spores to average 7,2x2.88. Harter also finds a rang3 in size of the 

 spores on various n.edia. 



The spores from old cultures are very different in appearance and vary 

 from the shortest that are reported from fresh cultures to spores that are 17 

 microns long. In old cultures there seem to be two types of spores, one being 

 the same as reported for the fresh culture and the other is darker, thick-walled 

 type, much wider and filled with guttules or oil drops. In one or two cultures 

 these large heavy walled spores are constructed in the middle and appeared as 

 if septate. 



The spores germinate in from 12 to 24 hours in agar and steri'e water, 

 though germination is generally very poor in the latter. A very noticeable 

 feature of the germination of the spores is the tremendous increase in s ze of 

 many of the spores which apparently occurs at the san e time as the germ tubes 

 are developed. In hanging drops of agar planted with spores of the average 

 size, germinating spores became nearly round and 17 microns long and 14 wide. 

 This swelling was not so prominent a feature in sterile water cultures though in 

 that medium they have been measured up to 12 microns wide. A few were 

 measured on the plants shortlj^ after they had germinated but these had on y 

 increased slightly. Spores that do not germinate or germinate very slowly do 

 not appear to increase in size. One lot of spores placed in a watch glass in ste- 



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