Mold Genera Research Articles

Two Genera of Molds with Low Temperature Growth Requirements

Two Genera of Molds with Low Temperature Growth Requirements

EVALUATION OF FUNGOUS DISEASE OF THE EXTERNAL AUDITORY CANAL

ALTHOUGH medical mycology preceded bacteriology by many years, there remains considerable misunderstanding concerning fungi and their relationship to man. This is particularly true about fungous disease of the external auditory canal. In the past decade considerable effort has been devoted to clarifying many of the aspects of this disease, but much work remains to be done. HISTORICAL REVIEW Mycetes have been studied for nearly three hundred years. In 1677 Hooke, with the aid of a magnifying lens, first discovered that the yellow spots on roses were living organisms. Micheli classified aspergilli as a genus of molds in 1729. In 1839 Langenbeck discovered that thrush was caused by a fungus. In the same year Schoenlein described the fungus causing favus. During the next thirty years the study of mycology flourished with the work on tinea circinata by Gruby in 1842, tinea versicolor by Eichstedt in 1846 and tinea pedis by Fox

ASPERGILLOSIS AND THE ASPERGILLI

PLEBEIANS among fungi, members of the great group Aspergillus have attained chief notoriety as vexatious laboratory contaminants. Considerably less attention has been focused on their aptitude as instigators of disease, while their role as serviceable implements of medicine has received minimal consideration. Aptly labeled weeds of the culture room, 1 over three hundred and fifty authenticated strains of aspergilli have been identified and delineated subsequent to their initial description in 1729. To warrant classification as an Aspergillus, a microscopic fungus must be comprised fundamentally of a stalk and a spore-bearing head. Innate minor variations occur in profusion, and though a species may be tentatively identified without undue difficulty, precise designation not infrequently entails recourse to a monograph devoted to this genus of molds exclusively. 1 The aspergilli prosper in diverse circumstances, and their ability to thrive on foodstuffs, soil and a host of seemingly barren mediums is attested to by

A Manual of the Aspergilli

THE publication, in 1926, of the monograph “The Aspergilli” by Thorn and Church was a landmark in the taxonomic study of this important genus of moulds. The fact that a re-working of the genus after twenty years has necessitated no fundamental change in classification is the best evidence of the sound scholarship which went to the writing of the monograph. Nevertheless, its very excellence gave other workers confidence, not only in identifying Aspergilli, but also in describing new species, with the result that a fair amount of new material has accumulated during the intervening years.

The Inhibition of Growth in Pollen and Mold under X-ray and Cathode Ray Exposure

It was the purpose of the following investigation to determine, within fairly wide limits, the point at which mature pollen grains, cultured in vitro, and mature spores of Penicillium become inactivated on exposure to x-rays and high voltage cathode rays. Such a piece of work seemed of interest and desirable for several reasons. So far as known by the authors, no systematic previous work has been undertaken in the x-raying or cathode raying of mature pollen with a view of determining its rate of “dying” and its point of inactivation. Considerable work has been done in the x-raying of mature pollen in the hope of producing mutations, and, while such work does not show promise of yielding nearly as fertile results in the form of genetic aberrations as may be obtained by the irradiation of pollen mother cells previous to the first reduction division, it is of interest that rough working data of permissible limits of exposure under given conditions should be at hand. Again, so far as known by the authors, no comparative work has been done on the resistance of pollen grains and mold spores to x-rays and cathode rays under the same conditions. Such a comparison should be of interest in view of the work which has been done in the x-raying and cathode raying of molds. It seemed worth while to investigate pollen as a biologic material of possible use in quantitative studies of radiation effects. And finally, little work appears to have been done, even with the molds, in the comparative investigation of the energy inputs of different forms of energy at roughly equivalent points of inhibition. Material Used.—After considerable preliminary work involving a large range of plant material, it was decided to confine the experiments with pollen to that of plants of the family Liliacæ, and to work principally with Lilium longiflorum because of its availability at all times and the ready genninability of its pollen under a fairly wide range of conditions. Several other species were included in the investigation, however, and found to be essentially similar in behavior. Chief among these were Lilium speciosum, L. regale, L. henryi, and L. auratum. Some work was also done with L. philadelphicum, L. canadense, L. sulfurum, and even the triploid day lily Hemorocallis fulva, but these species proved less satisfactory and were abandoned. Spores of a culture of the green-spored mold genus Penicillium were used, and proved so ready of culture and so thoroughly satisfactory in germination throughout that it was unnecessary to consider any further material. Sources and Character of Radiation.—Two sources of x-rays and one of cathode rays were used in this work, so selected that comparisons of inactivation might be made under fairly widely variant conditions.

Generic Concepts in the Pythiaceae and Blastocladiaceae

In a recent paper bearing the title A New Genus of Water Mold Related to Blastocladia the above genus is described as new by Coker & Grant.' The authors base the genus on a single species, S. dichotoma n. sp., which differs from the members of Blastocladia strikingly in that its thallus is normally and regularly septate. The species is compared with the four species of Blastocladia described by v. Minden in his treatment of the Blastocladiaceae in Kryptogamenflora der Mark Brandenburg,2 and a detailed description and figures are given. Unfortunately, several papers of importance in this connection have been overlooked. Butler 3 and Barrett,4 working independently, published almost simultaneously descriptions of two species which are clearly congeneric with that described by Coker & Grant. Butler called attention to the septate character of the thallus and founded the genus Allomyces to include his species which he named A. arbuscula n. sp. Barrett, approaching the study of his species from the cytological point of view, studied material both in toto and in paraffin section, and was able to demonstrate that the septa are merely perforated pseudo septa comparable to those of the Leptomitaceae. He was content to widen the limits of the genus Blastocladia to include his species which he named B. strangulata n. sp. Four years later v. Minden 5 incorporated the species in the genus