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VII. — On the Differentiation of Tissues in Fungi. 

 By Geokge Masses, F.R.M.S. 



(^Read 9th March, 1887.) 

 Plate VII. 



In the Eev. M. J. Berkeley's collection of fungi, now in the Kew 



Herharium, is a specimen marked " Polyporus pisoeJiapani Nees." 

 The plant is old and brittle, part of its substance having been reduced to 

 powder by minute fungus-eating beetles; nevertheless, the fact of its 

 being in this condition constitutes its special value in connection with 

 the present subject, that of illustrating in a marked manner the sharp 

 differentiation of its component hyphse into two distinct systems, 

 mechanical and reproductive. The first, being most durable, is almost 

 intact ; the latter much decayed, yet sufficient remaining to show clearly 

 its original arrangement. The mechanical component forms an un- 

 broken hollow cylinder in the stem near to its periphery ; its substance 

 is about half a line thick, and is surrounded at some little distance by 

 the indurated cuticle. At the apex of the stem this tube widens out 

 into a funnel-shaped body, which becomes broken up into a number of 

 ribs, radiating from the central portion to the margin of the pileus. The 

 substance of the stem portion of this mechanical sheath is solid, and in the 

 dry state as hard as cocoa-nut shell, but the ribs or radiating portions 

 of the pileus are hollow, taper to a fine point, and are sometimes con- 

 nected by transverse bars. The pileus, like the stem, is covered with a 

 cuticle. 



Examined microscopically, the mechanical ring is seen to be com- 

 posed of eseptate hyphse of a rich brown colour, and with very thick 

 walls ; in fact the cavity is in most cases obsolete. In the centre of the 

 ring the hyphae are rarely branched, closely compacted, and often more 

 or less polygonal in section from mutual pressure. Towards the outside 

 the hyphse are frequently branched, the larger branches being mostly 

 vertical and terminating abruptly in from two to several slender 

 filaments spreading in a flabellate manner. Numerous small branches 

 also originate from various points throughout the length of the large 

 hyphae, more especially those situated on the peripheral side of the 

 strengthening ring ; these small hyphse, by repeated branching, form 

 a plexus which becomes very intricate and densely compacted on the 



EXPLANATION OF PLATE YIL 



Fig. 1.— Portion of mechanical sheath of stem and pileus in Polyporus pisochapani; 

 natural size. 



Fig. 2.— Hyphfe from peripheral part of mechanical sheath of stem of P. pisochapani; 

 X 400 diam. 



Fig. 3. — Portion of meclianical sheath from stem of P. rugotus ; natural size. 



Fig. 4. — Laticiferous vessels from stem of Lactarius torminosus ; X 500 diam. 



Fig. 5. — Portion of transverse section through gill of Mussula f ceteris ; a a, cystidia 

 continuous with b b, laticiferous vessels ; X 500 diam. 



Fig. 6. — Portion of margin of gill of Goprinus atramentarius, showing a young 

 eystidium with hyaline protoplasm and a nucleus at a; 6. an old cystidium ; c, a 

 basidium with four spicules or spore-bearers : ouly two of the spores are shown. 



