Researches on fungi

Abstract

1 6 RESEARCHES OX FrXGT essential function of producing spores. Instances of sterility ot this kind have been noticed in two different species. A board was found in a cellar infected with Coprinus fimetarius, var. cinereus, and a small piece of it, bearing a young fruit-body, was sawn off, brought to the laboratory, and placed in a danip-chainber. After further development the fruit-body attained average size and form, but exhibited the peculiarity of being yellowish-white in colour instead of ashy grey. Upon examining the pileus with the microscope, I found that it was almost completely sterile. Only a few basidia had produced spores, whilst the great majority had remained in a rudimentary condition. The normal basidia were found chiefly at the pileus margin, but a very few Avere sparsely scattered over the general surfaces of the gills. Two other fruit-bodies subsequently appeared on the piece of board, but in these the spores were developed in the usual manner. Coprinus plicaiiloides'^A vas grown on sterilised horse-dung, from the surface of which its fruit-bodies Avere produced in large numbers, several each day for more than a month. At successive intervals about six fruit-bodies came up, Avhich seemed to be quite normal in size and form, but which Avere conspicuous among their companions by being Avhitish-yelloAV instead of grey. The microscope revealed the fact that the gills had failed to produce any spores. The basidia, surrounded by large paraphyses, had remained quite small ; they did not protrude beyond the general surface of the hymenium and, so far as I could observe, they had not even given rise to sterigmata. The cause of the occasional sterility of Coprinus fruit-bodies seems to be somcAvhat obscure. Since, however, the sterile fruit-bodies of Coprinus j)licatiloides grew in company Avith, and closely adjacent to, other fruit-bodies which Avere completely fertile, it seems safe to infer that the sterility was not conditioned by temperature, light, heat, moisture, or atmospheric gases. Perhaps the phenomenon is due to some accident happening to the mycelium at the time Avhen its contents are being poured into the young fruit-body. It is conceivable that, if the mycelium attached to the fruit-body were reduced in quantity, the fruit-body might suffer from starvation during its further development, and yet, in consequence of thê For iKJineiiclaturu of this species, ri,h infru, Cluxp. IV.

Identity of the Fungal Symbiont of Sirex Noctilio

“…Whether this clamped mycelium is formed from two compatible homokaryons, or from a homokaryon and a heterokaryon is not important, for it has been shown that the dikaryotization of a homokaryon by a heterokaryon-the Buller Phenomenon (Buller 1931)-is as good evidence of conspecificity as the formation of a heterokaryon from two homokaryons (Terra 1959;Boidin and des Pomeys 1961;Nobles and Frew 1962;Raper 1966). The essential feature of either process is that two compatible nuclei, capable of conjugate division, are brought together in one cell, and manifest their presence by producing hyphae bearing clamped septa.…”

Dikaryotization in Some Species of <i>Ravenelia</i>

“…The pycnia maybe functionally suppressed gradually during evolution from heterothallism to homothallism (Buller 1950). This was shown in Puccinia coronata Cda., a remarkable species which has 4 varieties, P. coronata avenae F. and L., P. coronata calamagrostidis F. and L., P. coronata bromi F. and L. and P. coronata elaegni F. and L., in which the first 2 varieties are heterothallic with well-developed pycnia (Allen 1932, Buller 1950. P. coronata elaegni is homo thallic with vestigial pycnia (Brown and Craigie 1938).…”

“…Both R. breyniae and R. sessilis produce respectively modera tely and well-developed pycnia, but both lack nectar ooze. Buller (1950) stated that presence of a pycnium cannot be a criterion to conclude that the species is homothal lic. On the contrary, Jackson (1935) opinioned that the presence of spermogonia and spermatia should not be considered indisputable evidence that the species is homothallic.…”

Effects of Variation in Water Potential on the Viability and Behaviour of Conidia of Peronospora Tabacina Adam

“…The unsatisfactory nature of disease-forecasting systems based on the determination of period of conidial liberation in the field (paddick, personal communication) may well be explained by the operation of such a mechanism. Sussman and Halvorson (1966) provide data showing a direct relationship between longevity and water content of fungal spores, but instances are known where dehydration rapidly leads to death (Buller 1933;Glaz 1955). In the present study, the results shown in Table 2 indicate a strong interaction between the effects of storage humidity and temperature.…”

“…INTRODUCTION Gregory (1961) has noted that, in air, spores gain orlose water rapidly. A number of studies (Buller 1909(Buller , 1922Falck 1927;Weinhold 1955) have been made on the sedimentation of spores in still air and the effects of desiccation on their rates of fall, but fewer authors have investigated the effects of desiccation on other properties of spores. Grindle and Good (1961) and Good and Zathurecsky (1967) have studied the effects of drying on the viability of germinating and germinated conidia of several fungi.…”