u6 



RESEARCHES ON FUNGI 



The area of a fruit-body is increased by marginal growth. 

 The peripheral walls of the interlamellar spaces protrude outwards 

 as crenatures, and more or less resemble the heels of slippers 

 placed side by side in a row (Fig. 43). These crenated walls 

 constitute growing regions by means of which the older gills are 



lengthened and new 

 A> ones added. Whilst a 



pileus is extending by 

 marginal growth, the 

 interlamellar spaces 

 gradually widen. 

 When a space has at- 

 tained a certain width, 

 it becomes divided into 

 two down the middle, 

 owing to the formation 

 within it of a new gill 

 which arises as a short 

 median downgrowth 

 from the pileus flesh 

 (Fig. 43, a). The upper 

 half of every new gill 

 is undivided, but the 

 lower half is made up 

 of two plates, the inner 

 surfaces of which are 

 in contact and clothed 

 with loose hyphse (cf. 

 Fig.4LE). Agill,whilst 

 still very short, occu- 

 pies an isolated, sub- 

 terminal position within the interlamellar space in which it has been 

 formed. However, as growth proceeds, its distal end gradually 

 approaches the pileus margin and eventually joins with it 

 (Fig. 43, a-e). All gills at their first-formed, stipe ends are 

 shallow and only partially divided. However, at their peripheral 

 growing ends they gradually become deeper and more divided, 



Fig. 43. — Schizophyllum commune. Piece of a pileus seen 

 from below showing the arrangement of the gills. 

 a-g, stages in gill development ; h. part of the 

 woolly layer covering the top of the pileus and here 

 extended over the pileus margin ; i, interlamellar 

 space. Semidiagrammatic: the gills are represented 

 as cut through transversely so that the surfaces of 

 section lie in one plane. About 13 times the 

 natural size. 



