GENERAL SUMMARY 469 



A pseudorhiza forms a link between a mycelium vegetating in a 

 buried root or other buried nutrient substance and the aerial part of the 

 fruit-body which produces and liberates spores. 



In most fungi with a pseudorhiza, e.g. Collyhia radicata, the pseudo- 

 rhiza is annual and unbranched ; whereas in C. fusipes, which is 

 exceptional, the pseudorhiza is perennial and branched. 



Every fruit-body which develops as a pseudorhiza arises in the first 

 instance as a tiny primordium at the surface of a buried root, etc. This 

 primordium becomes differentiated into the primordium of the pileus 

 and the primordium of the stipe. The primordium of the stipe then 

 becomes differentiated into the primordium of the stipe-shaft and the 

 primordium of the stipe-base or pseudorhiza. The pseudorhiza of the 

 very young fruit-body by intercalary growth elongates just beneath the 

 rudimentary stipe-shaft and pileus and, as it is negatively geotropic, it 

 pushes the rudimentary stipe-shaft and pileus upwards through the soil, 

 etc., until these organs reach the surface of the ground. Then the 

 pseudorhiza ceases to grow in length, the stipe-shaft elongates aerially, 

 the pileus expands, and the spores are liberated. 



The length of a pseudorhiza varies with the depth of the soil overlying 

 the buried root, etc., in which the mycelium of the fungus has vegetated. 



As a rule, a pseudorhiza thickens as it grows upwards so that it is 

 thickest just beneath the surface of the soil, i.e. in that position where it 

 is subject to the greatest mechanical strain. 



An account of the pseudorhiza of Collyhia radicata, Mycena gnleri- 

 culata, and Coprinus macrorhizus has been given. 



Collyhia radicata, lives upon the buried roots of Beeches, Oaks, Iron- 

 woods, Horse Chestnuts and, doubtless, other trees. Its pseudorhiza 

 may attain a length of 16 cm. 



The mode of development of the pseudorhiza of Coprinus macrorhizus 

 in all essentials resembles that of the pseudorhiza of Collyhia radicata. 

 The fruit-bodies of C. macrorhizus which are to develop a pseudorhiza 

 arise as primordia upon dense straw-dung situated a little distance below 

 the general surface of a manure pile, etc. The pseudorhiza by intercalary 

 growth and response to the stimulus of gravity then pushes the rudiment- 

 ary stipe-shaft and pileus through the overlying straw, etc., to the surface 

 of the manure pile, and there the stipe-shaft and pileus complete their 

 development aerially in the usual way. 



In Coprinus macrorhizus, when a young pileus and enclosed aerial 

 stipe-shaft are injured, the pseudorhiza may branch and give rise to 

 several new but smaller fruit-bodies. 



Chapter II. — The myceUum of Collyhia fusipes vegetates in the wood 

 of subterranean roots of Beeches and Oaks, and gives rise to fruit-bodies 

 which are attached to these roots by means of a pseudorhiza. 



The pseudorhiza of Collyhia fusipes is perennial and, in the course of 

 successive years, owing to branching and lateral fusion, may become 



