GENERAL SUMMARY 



THE FOLLOWING IS A SUMMARY OF THE MORE IMPORTANT 

 RESULTS OBTAINED DURING THE INVESTIGATIONS 



PART I 



Chapter I. — By means of hyphal fusions (anastomoses) the mycelium in 

 many species of Ascomycetes, Basidiomycetes, and Fungi Imperfecti 

 becomes converted in an early state of development into a three- 

 dimensional network. Hyphal fusions are also present in the fruit- 

 bodies of these fungi. The advantages accruing to a mycelium and to 

 a fruit-body through the existence of hyphal fusions have been briefly 

 summarised. 



It is important to distinguish between (1) a hyphal contact, (2) a hyphal 

 adhesion, and (3) a hyphal fusion. Only in a hyphal fusion do the two 

 masses of protoplasm of the two hyphae become confluent. 



Vegetative fusions promote vegetative processes, e.g. the conduction of 

 food materials, the transmission of stimuli, etc., while sexual fusions assist 

 the coming together of nuclei destined to co-operate in a sexual process. 



Parasitic fusions, e.g. those between Chaetocladium or Parasitella and 

 certain Mucorineae, bring the protoplasm of the parasite and of the host 

 into continuity and thereby promote the nutritive processes of the 

 parasite. 



In a single mycelium hyphal fusion sets in in the older parts where the 

 culture medium is becoming exhausted and, in general, the process is 

 promoted by conditions of starvation. 



The mycelium as a whole strives to become a three-dimensional 

 network, but a network of not too fine a mesh. The actual formation of 

 hyphal fusions seems to alter the physiological condition of a mycelium 

 in such a way that the mycelium in the end ceases to produce hyphal 

 fusions. The formation of hyphal fusions in a mycelium as a whole is 

 well regulated. 



It is characteristic of both vegetative and sexual fusions that hyphae 

 or sexual organs destined to fuse act upon one another at a distance. 

 The observations made by previous workers on this phenomenon have 

 been reviewed. 



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