28 



RESEARCHES ON FUNGI 



protoplasm in the two fusing hyphae come into contact with one 

 another, melt together, and thus establish protoplasmic continuity 

 from one hypha to the other. 



Whilst the mycelium is growing rapidly at its periphery, hypha- 

 to-hypha fusions take place only between lateral hyphae in the 



Fig. 13. — Diagram showing successive stages in a hypha-to -hypha fusion in one of the 

 Higher Fungi (Pyrenomycetes, Discomycetes, Hymenomycetes, and Gastromy- 

 cetes). A, two ordinary lateral vegetative hyphae, elongating at their apices, 

 by chance are approaching one another. B, growth has continued and the two 

 hyphae have now come sufficiently close together to stimulate one another 

 tropically. C, as a result of mutual stimulation, the ends of the hyphae have 

 changed their direction of growth and are now growing toward one another. 

 D, the ends of the two hyphae are rapidly approaching one another. E, the 

 ends of the hvphae have met. F, fusion has taken place. Time which elapses 

 between stage A and stage F varies with the rate of growth of the hyphae, but 

 is often of the order of one hour. 



older more internal parts of the mycelium where the medium is 

 partially exhausted. The peripheral radial hyphae, so long as they 

 are vigorously elongating, never fuse with one another. In media 

 becoming exhausted as a whole hypha-to-hypha fusions may take 

 place even between peripheral hyphae. 



Hypha-to-Peg Fusions.— A hypha-to-peg fusion takes place 

 between the end of a younger hypha which at first grows freely and 

 independently in the culture medium and a special peg-like hypha 



