28 TEXT-BOOK OF FUNGI 



is said by Dangeard to compensate for the absence of the 

 mingling of protoplasm in his supposed sexual process. 



Ward investigated this phenomenon in detail in the 

 hyphae of a species of Botrytis in hanging-drop cultures. 

 The fact that a hypha could be deflected through a right 

 angle to fuse with another hypha suggested the idea that 

 some attraction is exercised. Hyphae do not always fuse 

 when they cross each other, and to bring about the neces- 

 sary attraction it is assumed that the hyphae must contain 

 a ferment substance in the necessary quantity or condition 

 of action, or both, before two hyphae can fuse together. 

 Another peculiar method of coalescence characteristic of 

 the Basidiomycetes, but not strictly confined to this group, 

 is known as clamp-connections. This arrangement is only 

 met with where the hyphae are broken up into cells by 

 transverse septa. A protuberance forms laterally on the 

 wall of a hypha, close to a transverse septum, and increases 

 in length until its apex comes in contact with the adjoining 

 cell of the hypha situated on the other side of the septum ; 

 the point of the outgrowth and also that of the wall it 

 touches are absorbed ; thus open communication by means 

 of this neck is set up between two cells of a hypha that 

 were originally separated by a transverse wall. At a later 

 stage one or both openings from the cells of the hypha 

 communicating with the lateral clamp are again closed. 

 These clamp-connections are arranged in a spiral manner 

 around the hypha, each one being a little to the right or 

 left of the one below or above it. 



The combination of hyphae to form a tissue is effected 

 by the intertwining of the component threads, and not 

 by cell-division as in the higher plants, where successive 

 septae are arranged in two or three directions of space ; 



