THE FORMATION OF HYPHAL FUSIONS 



45 



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is represented a normal hypha in which the hook is directed back- 

 wards, at B there is represented a theoretical hypha, in general similar 

 to A but having the hook of the clamp-cell directed forwards instead 

 of backwards. 



Let us now compare the disposition of the nuclei in the normal 

 hypha A and in the unnatural hypha B. At once we see that, 

 whereas in A the ultimate cell contains two nuclei and the penulti- 

 mate cell one, in B this is reversed, for here the ultimate cell contains 

 one nucleus and the penultimate cell two. 



The disposition of the nuclei in A and B in Fig. 22 is, of course, 

 only temporary ; for, as 

 soon as the clamp-cell 

 fuses with a cell of the 

 main hypha, the penulti- 

 mate cell in A and the 

 ultimate cell in B both 

 come to contain a pair of 

 nuclei. 



As growth continues 

 and new clamp-con- 

 nexions are formed, in 

 such a normal hypha as 

 A in Fig. 22 there are 

 always two nuclei in the 

 ultimate growing cell ; 

 whereas, in such an un- 



,4- 



Fig. 21. — Diagram showing, from left to right, five 

 successive stages in a conjugate nuclear 

 division associated with the formation of a 

 clamp-connexion in a hypha of a diploid 

 mycelium of Coprinus lagojms ( = C . fimetarkis 

 of Mile Bensaude) as represented by Mile 

 Bensaude. For a detailed explanation vide 

 Vol. IV, p. 155. Copied for the author by 

 Dr. Nellie Carter. 



natural hypha as B, the 



ultimate growing cell would contain sometimes two nuclei and 

 sometimes one, the reduction from two nuclei to one taking place 

 during the completion of the last half of the development of each 

 new clamp-connexion. 



In Coprinus lagojms, in respect to the formation of clamp- 

 connexions on a leading hypha, the following time-data have been 

 determined: (1) a new clamp-connexion is formed about every 

 50 minutes ; (2) the time required for the formation of a 

 single clamp-connexion is about 23 minutes ; (3) the time which 

 elapses between the formation of the first septum across the 



