SCHIZOPHYLLUM COMMUNE 119 



thus permitted to straighten themselves again. The straightening 

 out of the gill plates, however, is brought about by something 

 more than mere cell-wall imbibition and stretching. This is 

 proved by the fact that the dry gills of dead fruit-bodies are not 

 capable of becoming entirely uncurled. Partial recovery of the 

 gills was observed : (1) In fruit-bodies which had lost their vitality 

 when kept for sixteen years in the dried condition, and (2) in fresh 

 fruit-bodies which were dried and then caused to absorb a solution 

 of 1 per cent, corrosive sublimate through their upper surfaces. 

 The first and major part of the straightening out of the gills we 

 may regard as a mechanical process connected with the swelling 

 of cell-walls. On the other hand, the final apposition of the two 

 plates of each gill appears to be brought about by the resumption 

 of turgidity by the hymenial and subhymenial elements. The finer 

 part of the whole readjustment, according to this interpretation, is 

 traceable to the semipermeable properties of living protoplasm. 



The division of the gills of Schizophyllum into two plates is 

 significant in that it permits of the hymenial surfaces being pro- 

 tected during periods of drought. The rapid curling up of the gill 

 plates on the advent of dry weather must serve to check the rate 

 of loss of water from the fruit-body by limiting the amount of 

 gill surface exposed to the outer air. This closing oft' of most of 

 the transpiring gills at the beginning of desiccation, finds its analogy 

 in the curling up of the leaves of many xerophytic Phanerogams 

 under similar atmospheric conditions. However, I am not inclined 

 to think that reduction in the rate of transpiration is the chief 

 advantage gained by the opening out of the gill plates. Periods of 

 drought are often very long, and when they occur it may be of 

 considerable advantage for a fruit-body to have its delicate hymenial 

 surfaces, covered as they are with millions of spores, made as inac- 

 cessible as possible to various small marauding animals. However, 

 the exact ecological significance of the opening out of the gill 

 plates would best be elucidated in the tropics, where the genus 

 Schizophyllum is richest in species. 



