374 RESEARCHES ON FUNGI 



as is actually the rule, there are always two nuclei in the terminal cell 

 and the nucleoplasmic ratio is never greatly disturbed and remains 

 relatively constant. 



Mile Bensaude's second mode of formation of a clamp-connexion, 

 based on cytological evidence, finds no support in the author's observa- 

 tions on the stages in the development of living clamp-connexions and 

 is therefore not accepted by him. 



The evidence adduced (1) by Mile Bensaude for regarding certain 

 fusions in the mycelium of Coprinus lagopus as end-to-side ones and 

 (2) by Hein for regarding the large vascular hyphae of the mycelial cords 

 of Psalliota campestris as owing then origin to side-to-side fusions of 

 a number of hyphae of smaller diameter is regarded by the author as 

 unsatisfactory. 



The problem of the means whereby hyphae taking part in hyphal 

 fusions influence one another at a distance has been discussed but not 

 solved. 



Whether or not, in Botrytis cinerea, Corticium solani (= Rhizoctonia 

 solani), etc., heterocaryosis actually comes into existence after hyphal 

 fusions have been formed between the mycelia of two different strains 

 has been left an open question. 



Chapter II. — The history of our knowledge of protoplasmic streaming 

 in fungi has been reviewed. 



Arthur and Schroter stated that in Rhizopus nigricans, when streaming 

 is actively taking place in the centre of a hypha in one direction, a thin 

 peripheral sheath-like non- vacuolated layer of protoplasm can sometimes 

 be seen moving in the opposite direction. Andrews held that the proto- 

 plasm in a hypha at any one time moves in one direction only and never 

 in opposing directions. The author's observations confirm those of 

 Arthur and Schroter. 



The history of our knowledge of the existence of a central pore in 

 each septum of the mycelia and fruit-bodies of Ascomycetes, Basidio- 

 mycetes, and Fungi Imperfecti has been reviewed ; and, in particular, 

 attention has been called to the work of Wahrlich (1893). 



The author has observed protoplasmic bridges passing through the 

 central pore of septa in mycelial hyphae of Fimetaria fimicola and 

 Rhizoctonia solani (Corticium solani). 



All the living cells which make up an individual fungus plant are 

 connected together so as to form a single mass of protoplasm. A realisa- 

 tion of this important fact helps us to understand not merely the 

 phenomenon of protoplasmic streaming in the mycelium of Discomycetes, 

 Pyrenomycetes, and Hymenomycetes, but also how it is that a multi- 

 cellular fungus can develop and react to external stimuli in a unitary 

 manner. 



Protoplasmic streaming in septate mycelia has been observed by the 

 author in Fimetaria fimicola, Oelasinospora tetrasperma, Pyronema con- 



