Annual Report Volume 17 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ...rigidum (Pers.) Sacc. A species of Graphium was found discoloring the sapwood of lumber made from Quercus rubra L. in Indiana. This, when isolated in pure cultures, grew readily on the sapwood of pine, oak, gum and ash, and on vegetable agar media, also on potato, bean, and other vegetables in test tubes. The fungus corresponds quite closely to the description of Graphium rigidum (Pers.) Sacc., with the exception that it has in addition a conidial stage, the conidial clusters taking the closed form. The following emended description of this species is now given from artificial cultures on wood and agar media: --Mycelium. Cultures of both primary and secondary conidia sown in ordinary vegetable agar media germinate in a few hours, and in two days begin to bear an abundant crop of secondary conidia in clusters of a type similar to those of G. smaragdinum, which collect as rapidly as they develop into rounded, mucilaginous clusters (pi. 7, f. 7). The filaments of the mycelium are hyaline at first, but in a few days form a brown pigment in the older portion, and throw up stalked heads bearing the primary conidia. These vary from a stalk consisting of two or three filaments with a small globular or flattened oval head, to one consisting of many, with a much larger head (pi. 7, f. 6). Secondary Conidia. Secondary conidia are borne on both simple and branching hyphae by abstriction of the ends, and as fast as they are formed adhere together in masses resembling Cephalosporium. Theyare colorless, thin-walled, and are usually free from guttules and granules. They measure 3/ to 4.5a by 1/ to 1.5/ (pi. 7, f. 8). Primary Conidia. Primary conidia are elliptical, resembling in appearance and form the secondary conidia. They are hyaline, and measure 3.5/..