THE PERENNIAL PSEUDORHIZA 385 



upon the buttress-root of a Beech, was as large as a child's fist, 

 blackish both without and within, and spongy in texture. After 

 I had excavated it, I broke it up into five pieces all of which are 

 shown in Fig. 192. This dark body appeared to be made up of a 

 great number of irregularly fused, rather brittle, persistent stipe- 

 bases or pseudorhizae ; and its formation was doubtless due to 

 several years' growth. As it was black and spongy in texture, it 

 resembled a sclerotium not a little ; and it was probably such a 

 large black irregular structure as this that Leveille had in mind 

 when he stated that the fruit-bodies of Collybia fusipes sometimes 

 spring from a sclerotium. However, we ought not to regard such 

 a structure as a sclerotium : firstly, because it is composed of basal 

 parts of fruit-bodies and not of mycelium ; and, secondly, because 

 there is no evidence that, if isolated from the root to which it is 

 attached, it could independently produce any fruit-bodies. Doubt- 

 less it contains a certain amount of reserve food materials ; but, 

 in the main, it is not a food reservoir but only a conductor of food 

 materials from the mycelium in the wood of the root to the new 

 fruit-bodies which develop at its apex. 



Evidence that the Pseudorhiza Persists. — The evidence that 

 goes to prove that the stroma-like fungal strand connecting a fruit- 

 body cluster of Collybia fusij)es with the root of a tree is really a 

 persistent pseudorhiza or sympodium of pseudorhizae is of two 

 kinds : (1) field observations, which show that a cluster of fruit- 

 bodies often comes up above a root at exactly the same spot where 

 a cluster appeared the previous year, and (2) comparative observa- 

 tions upon the structure of pseudorhizae. 



(1) Field observations. In 1916, Miss E. M. Wakefield and I 

 made careful notes upon the positions of twenty Collybia fusipes 

 fruit-body clusters which had come up above the roots of Beeches 

 and Oaks in Queen's Cottage Grounds, Kew Gardens ; and, in order 

 to find out whether or not new clusters would appear in 1917 at 

 exactly the same places as clusters had appeared in 1916, we drove 

 into the ground alongside of each cluster a long metal skewer. In 

 1917, on account of the war, I was unable to return to Kew, and 

 Miss Wakefield was able to visit the skewers only once. This 

 visit, which was made in early autumn, yielded positive results, 



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