206 AGRICULTURAL EXPERIMENT STATION. [Jan. 



threads, as the microscope shows. Later, there appear in 

 these cavities, among tlie slender threads, chib-shaped 

 structures, in each of which are gradually developed eight 

 colorless winter spores, which become ripe and capable of 

 germination by the middle of January. Crozier gives * a 

 considerably later date for the maturity of the spores in 

 Michigan ; but the above, given by Dr. Farlow for eastern 

 Massachusetts, has been found by the writer to be also 

 correct for Amherst. These spores may continue in the 

 cavity for some time, but eventually escape, probably by a 

 pore formed at the central depression before mentioned. 



A fully developed knot ordinarily shows no spores 

 remaining by late spring or summer. 



Fig. 1 shows a magnified section through three of the 

 spore cavities or fcrithccia of the fungus, containing the 

 club-shaped spore-sacs or asci. In Fig. 2 are represented 

 two spore-sacs, with their contained spores, and two of the 

 sterile threads or paraphyses among which they grow. 



When obtaining the winter spores in quantity by scraping 

 the freshly cut surface of a section across many perithecia, 

 I have nearly always found mixed with them a small pro- 

 portion of the globular or slightly elliptical brownish bodies 

 shown at Fig. 4, a; but I have not yet met with them in 

 spore cavities. 



Studies of the development of the three above-described 

 spore forms have been carried on in the laboratory with 

 interesting results. The following account gives a general 

 outline of the progress and present status of the work. 

 After its completion, a detailed account of the investiga- 

 tions, with their results, both theoretical and practical, will 

 be published, with full illustrations, in a suitable form. 



The winter spores, when sown in water and kept in a 

 moist chamber, begin to germinate so promptly that they 

 show germ tubes of some length at the end of one day 

 (Fig. 3, a) ; while in two da3's as many as three threads, 

 one of which has taken the lead, as a rule, and has become 

 several times as long as the spore, may have developed 

 (Fig. 3, h). The principal threads usually originate from 



~~ ' ,* Botanical Gazette, 1885, p. 368. 



