Take-off of Mould Spores in Relation to Wind Speed and Humidity

Using horizontal tube-cultures of various moulds belonging tothe genera Thamnidmmt, Phymatotrichum, Trichotheciwm, Ptptocephalis,Trichoderma, Mucor and Mycogone, the take-off of dispersal units(usually spores) under the influence of air currents of variousspeeds and of different humidities has been studied. It is foundthat in all the dry-spore forms the number of spores set freeincreases as the speed of the air stream rises. Further, atany given air-stream rate, the numbers of spores set free aregreatest in the first interval of time and rapidly fall offin subsequent intervals. In all species, spores are more readilyset free in air streams of relatively low as compared with thoseof relatively high humidity. Although Trichoderma viride hasbeen regarded as a slime-spore fungus, its conidia can readilybe blown from the conidiophores. No spores could be inducedto take off from Mucor ramarmianus even at the highest air speedsused.     

Transpiration and Water Uptake in the Fruit Bodies of Some Hymenomycetes

The relationship between relative humidity and transpiration was studied in the basidiocarps of Coprinus, Amanita, Agaricus, Tricholoma, Collybia and Polyporus. Transpiration decreases with an increase in the humidity and there is virtually no transpiration in nearly saturated air. To determine the relationship between uptake and transpiration, stipes were immersed in solutions of various osmotic ally active substances and inhibitors. Results showed that uptake has no influence on the transpiration. Additional data suggested that uptake in a detached basi-diocarp proceeds as long as the fruit body is young and healthy. Studies with fluorescein dye and mannitol showed that most transpiration occurs at the surface and edges of the hymenium.     

Liberation of asexual propagules in the Mucorales

The liberation of asexual propagules in the Mucorales was investigated by means of wind-tunnel experiments. Some species do not liberate propagules into an air stream, others liberate single spores or groups of spores. The effect of the relative humidity of the air stream upon propagule liberation has also been considered.