THE FORMATION OF HYPHAL FUSIONS 



35 



Some of the details in the formation of a clamp-connexion in 

 Coprinus sterquilinus and C. lagopus are shown semi-diagrammatic- 

 ally in Fig. 18, where it will be seen : (1) that the hook grows back- 

 wards and comes almost or quite into contact with the main hypha 

 (A and B) ; (2) that -two septa are formed, one across the main 

 hypha and the other across the base of the hook, and that both 

 have a small central pore x such as is characteristic for the septa of 



aSsSS 



.''■■'■~> ■':'■*'. 



Fig. 18.- — Semi-diagrammatic median longitudinal sections of a hypha of Coprinus 

 sterquilinus or C. lagopus showing successive stages in a hook-to-peg fusion during 

 the formation of a clamp-connexion. A, part of the terminal cell in an elongat- 

 ing hypha in which a clamp-connexion is being formed ; already a hook has 

 grown outwards and backwards from the main hypha. B, the hook has grown 

 toward the main hypha and is almost or quite in contact with it ; also two septa 

 have been formed, one across the main hypha and the other across the base of 

 the hook ; each septum (as is usual for all septa in the Hymenomycetes) has a 

 small central pore occupied by a protoplasmic bridge. C, the main hypha has 

 sent out a peg, p, opposite the apex of the hook. D, the apex of the hook and 

 the apex of the peg have now flattened out against one another. E, the double 

 wall between the hook-cell and the peg has broken down and now there is 

 protoplasmic continuity between the hook-cell and the peg. In a certain hypha 

 of C. lagopus in which the formation of a clamp -connexion was observed, the 

 time at which the hook began to be formed was taken as zero in the time-scale 

 and the times at which the successive stages were attained were found to be 

 as follows : A, 3 minutes ; B, 15 minutes ; C, 21 minutes ; D, 22 minutes ; 

 E, 23 minutes. In C. sterquilinus and C. lagopus the thickness of the hyphae 

 in which the formation of clamp-connexions was observed was about 5-0/u and 

 2 • 5 /u respectively. 



the mycelium of Hymenomycetes in general (B) ; (3) that the main 

 hypha sends out a peg in the form of a blunt process opposite to the 

 apex of the hook (C) ; (4) that the peg grows in size and that the 

 end of the peg and the end of the hook press against, and flatten out 

 against, one another (D) ; and, finally, (5) that the double wall 

 between the hook and the peg breaks down and disappears so that 



1 For a full description and a treatment of the function of septal pores vide infra. 

 Chapter II. On account of the small scale, pores have not been shown in the cell- 

 walls in any illustration in this chapter other than Figs. 18, 19, and 22. 



