PSALLIOTA CAMPESTRIS 



443 



which tend to form cell-chains, greatly exceed in size even the 

 largest elements of the hymenium and subhymenium. 



FIG. 150. Psalliota campestris (wild form). Cross-section of a living gill of a 

 fruit-body just expanded, drawn with the camera lucida. In cutting the 

 section all the spores on the basidia nos. 1, 2, 3, 4, and 5, were knocked off 

 their sterigmata except the one shown on basidium no. 1. The extreme top 

 and bottom of basidium no. 6 were not drawn owing to an oversight, and have 

 been completed semi-diagrammatically ; otherwise all elements are repre- 

 sented as seen. Chief object of drawing : to show the relations of the hymenium 

 with the subhymenium. h, the hymenium ; s, the subhymenium ; t, part of 

 the trama. Nos. 1, 2, 3, 4, and 5, present-generation basidia. No. 6, a coming- 

 generation basidium. Nos. 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, and 18, future- 

 generations basidia, possibly with the exception of nos. 7 and 9 which may be 

 paraphyses. Nos. 19, 20, 21, and 22, and possibly also nos. 7 and 9, are para- 

 physes. The subhymenium consists roughly of four layers of cells (reading 

 from left to right) : the highest layer, usually supporting paraphyses, I, II, 

 III, IV, V, and VI ; a second layer, VII, VIII, IX, X, XI, XII, XIII, XIV, 

 XV, XVI, XVII, XVIII, XIX, XX, and XXI ; a third layer, XXII, XXIII, 

 XXIV, XXV, XXVI, XXVII, XXVIII, XXIX, XXX, XXXI, XXXII, and 

 XXXIII ; a fourth layer of a few cells only, XXXIV, XXXV, and XXXVI. 

 Some of the basidia arise deep down in the subhymenium, e.g. nos. 2 and 4 

 which spring from the cells XXIII and XXIX respectively : the bases of these 

 basidia are enveloped by upper subhymenial cells. It is evident from a 

 study of this Figure that there is no sharp plane of demarcation between 

 the hymenium and subhymenium. Magnification, 1,040. 



