B. O. Dodge

The Mechanics of Sexual Reproduction in Neurospora

The course by which a perithecium of Neurospora reaches full maturity is marked by three rather distinct stages of develop? ment. First there appears the perithecial fundament, the ascogonium. This is quickly surrounded by several layers of compact hyphal growth to form the incipient ascocarp. Nuclei of opposite sex reaction then come together in the ascogenous cells if these cells do not already contain both kinds, as is normally the case in N. tetrasperma. This stimulates further growth of the fruit body, the differentiation of wall tissue, the formation of the ostiolar papilla, and finally the development of ascogenous hy? phae. Fertilization is consummated with nuclear fusion in the ascus. This is followed by the reduction divisions and the delimitation of ascospores.

Breeding Albinistic Strains of the Monilia Bread Mold

SummaryAsci from cultures in which strains Arl.6 and Arl.10 of Neurospora sitophila are mated are not all alike. Some asci produce spores which differ primarily only as to their sex. All 8 spores i...

A Further Study of the Morphology and Life History of the Rose Black Spot Fungus

One who attempts to grow hybrid roses in this part of the country is apt to find sooner or later some of them being defoliated by the black spot fungus, Diplocarpon Rosae. For example, at The New York Botanical Garden it has been observed for several years that certain varieties among our most beautiful roses such as Los Angeles, Mrs. Henry Bowles, Felicity and Padre, always show some spotting in spite of the fungicides which have been applied rather frequently. On the other hand, there are those roses like Red Radiance, Ethel Sommerset, Mrs. C. W. Edwards, La France, Radiance and others, which under the same treatment scarcely ever show black spot. The writer has been asked frequently why it is that the Red Radiance, for example, is comparatively resistant to this parasite. Is it because, as some say, the leaves probably have a cuticle which the fungus cannot penetrate? Or is it due to something more fundamental and inherent in the cytoplasm so that the fungus is unable to live even though it may readily penetrate the cuticle and so cause only a mere flecking. This is among the problems being studied, and some information on this question obtained as a result of preliminary experiments is also presented at this time.

The Ascocarpic Stage of Species of Scopulariopsis

The asexual fructifications of ascomycetes are as often as not misleading when it comes to determining relationships. Monilia may be the conidial stage of certain species of Sclerotinia, a discomycete, on the one hand, or it may be connected with species of Neurospora, a pyrenomycete, on the other. Botrytis may be the asexual stage of certain other species of Sclerotinia in one case, but be connected with a Lachnea, quite a different type of discomycete, in another case. Much of our knowledge of the morphology of the ascocarp of Aspergillus and Penicillium dates back to the time of de Bary, Zukal and Brefeld, and to the cytological work of Fraser and Chambers and of Dale. The group Plectascales may be a heterogeneous one including forms of doubtful relationship. Should Thielavia as represented by T. basicola and T. terricola be included along with Aspergillus in this group? Neither species of Thielavia has a conidial stage and their carbonaceous ascocarps are quite unlike those of either Aspergillus or Penicillium. The disposition of the ascogenous hyphae and asci is such, however, as to suggest in a general way a relationship. The writers have recently had under observation two species of ascomycetes which in the manner of the origin and develop? ment of the ascogenous hyphae and asci, taken in connection [Mycologia for July-August (23: 147-311) was issued July 1, 1931] 313

Volutella Buxi and Verticillium Buxi

Culture experiments have proved that, as Juel first reported, Volutella Buxi and Verticillium Buxi are distinct species. Attention is called to a number of exsiccati specimens variously distributed...