1893.] PUBLIC DOCUMENT — No. 33. 221 



son's greenhouse, a young rotting cucuml^er was found which 

 bore, besides the white Sderotinia mycelium, the dark spore 

 threads and abundant spores of a Botvytis form, the question 

 of its genetic connection with the Sderotinia became a very 

 interesting one. The specimen was carefully preserved, and 

 the spores were obtained quite pure for a series of cultures. 

 When sown on prune-gelatine they produced a luxuriant 

 mycelium, whose growth was accompanied b}^ a characteris- 

 tic formation of crystals of oxalate of lime. From this 

 mycelium were developed numerous attachment organs, like 

 those above described, and spore threads, with spores, iden- 

 tical with the original Botrylis form. Except for its phys- 

 iological similarity in the production of oxalate of lime and 

 the structural similarity of its attachment organs, there was 

 no ground for suspecting any connection between this form 

 and the Sderotinia. Sown on bread saturated with prune 

 infusion, the original spores gave results precisely similar to 

 those above described. When sown on a solid block of 

 sterilized potato in a test tube, however, they produced not 

 only abundant attachment organs and spore threads, but 

 also sclerotia. Nine days after the beginning of a culture, 

 very dense masses of mycelium were seen at the angles of 

 the block of potato, and two days later well-formed young 

 sclerotial masses occupied the same positions. These ma- 

 tured fully, and showed, in their microscopic structure and 

 in their reaction for glycogen, complete identity with the 

 sclerotia developed from the ascospores of the Sderotinia. 

 The sclerotial masses did not form a rind on the side next to 

 the potato, and remained closely adhering to it; but this 

 was probably due merely to the character of the substratum. 

 It is of interest to note that the spores of the second genera- 

 tion from the original material failed to produce sclerotia 

 on any of the substrata mentioned ; but the positive evi- 

 dence of a single culture is worth any number of failures. 

 There is no possibility of the contamination of the success- 

 ful cultures by ascospores, for at the time they were made 

 not a single Sderotinia cup was or ever had been in existence 

 in the laboratory. The culture was made with a drop of dis- 

 tilled water containing a few spores, and showed no evidence 

 of the presence of any other mycelium or spore form than 



