2o6 



Journal of Agricultural Research 



Vol. XIII, No. , 



Fig. I. — Phomopsis kalmiae: A , Germinating 

 pycnospores; B, types of spores produced 

 by the fungus. X 950. 



GERMINATION TESTS 



Practically all the transfers made during the work with this fungus 

 have been germination tests, since the extruded spores were in almost 

 every instance used to make the transfers. Spores freshly extruded 

 germinate very promptly under favorable conditions — that is, within 24 

 hours they usually send out a germ tube from the blunter end, and 

 rarely two, one from each end (fig. i, A). Spores which are older and 



which have become dried of course ger- 

 minate more slowly, though the age 

 and condition of the spores and time 

 required for germination vary in this 

 direct ratio only up to a certain point. 

 Long threads of spores which had stood 

 in corn-meal flask cultures for 13 months 

 and which had become very dry and 

 brittle germinated about as soon as 

 spores taken from similar cultures 6 to 

 8 weeks old. Steamed-potato cylinders 

 and steamed corn meal in flasks have 

 proved to be the best media for rapid 

 germination. 



Germination is very slow in distilled 

 water, and only a small percentage of 

 the spores introduced germinate at all. After 48 hours but very few 

 spores are found which have produced a germ tube. Even after five 

 days there is rarely any growth visible to the naked eye, but a micro- 

 scopic examination shows a limited germination. Possibly i to 5 per 

 cent of the spores are seen to have formed short germ tubes, very rarely 

 branching. Very frequently the germinating spores showed peculiar 

 swellings or knobs (appressoria ?) at the end of the germ tube (fig. i, A). 

 Several experiments were made by adding varying quantities of ether 

 to sterile distilled water containing the spores, and very small amounts 

 stimulated germination to a marked degree. 



The germination of the sclerotia-like bodies, or sterile pycnidia, was 

 also tested. With sterile forceps the upper portion of these erect aerial 

 bodies was broken off and placed upon potato cylinders, corn-meal agar 

 slants, etc. Growth occurred in practically all of the tests made with 

 these bodies. Plates were also poured from corn-meal agar tubes, 

 in which some of these sclerotial bodies had been placed, so that growth 

 could be watched under the microscope. Plate 17, C, show^s the appear- 

 ance of a cross section of such a body after growth had started. 



PHYSICAL AND BIOCHEMICAL CHARACTERS 



Reduction of nitrates. — Cultures in Dunham's solution with potas- 

 sium nitrate were tested after 5, 10, 15, and 20 days' growth by the 

 starch-iodin method. No blue color reaction resulted, showing the 

 absence of nitrites, as is also shown below under "Indol production." 



