3o8 RESEARCHES ON FUNGI 



Fig. 10.— The backwardly directed end of the hook has now fused with the 

 subterminal hyphal cell, thus completing the formation of the clamp-connexion 

 and allowing the (AB) nucleus which was imprisoned in the hook-cell to escape 

 into the subterminal hyphal cell and there join its mate, the {ab) nucleus. 



YiQ. 11. The diploidised hypha with the clamp-connexion and its branch have 



now considerably elongated, and the two pairs of conjugate nuclei have crept along 

 them toward their centres. Both of these pairs are about to divide conjugately. 



Fig. 12. — The two cells containing conjugate nuclei shown in Fig. 11 have now 

 developed into a diploid mycelium consisting of seven cells which are increasing in 

 number. In the two upper right hyphae of the diploid mycelium the development 

 of clamp-connexions and conjugate nuclear divisions are in progress. In the 

 diploid myceUum, as contrasted with the haploid mycelium, note the septa accom- 

 panied by clamp-connexions, the narrow-angled mode of branching, the entire 

 absence of oidiophores and oidia, and the presence in every cell of a pair of 

 conjugate nuclei. The diploid mycelium after growing further, might give rise 

 to a diploid fruit-body like that shown above. The spores which the fruit-body 

 is represented as discharging would consist of all of the four possible sexual kinds : 

 (AB), (ab), {Ab), and {aB). 



For the sake of simplicity, in Figs. 1-12 only one diploidised cell and its 

 development into a diploid mycelium has been represented ; but, in reality, two 

 haploid mycelia of opposite sex mutually diploidise one another so that a pair 

 of conjugate nuclei comes to be present in the end-cell of every growing hypha. 

 Thus every end-cell, after being diploidised, could have been represented as 

 developing in a manner similar to that shown for the single diploidised cell of 

 Fig. 4. 



PLATES III AND IV 



Figs. 1-12 in Plates III and IV represent an attempt made by the author, in the 

 Light of our present knowledge of the sexual processes of the Hymenomycetes, to 

 visualise diagrammatically in Coprinus lagopus the mode of union of a diploid my- 

 celium {AB)-]-{ab) with a haploid mycelium (ab), and some of the stages involved in 

 the diploidisation of the haploid mycelium {ab) by the diploid mycelium {AB)-{-{ab). 



Fig. 1. — Two mycelia are represented : on the left is a diploid mycelium 

 {AB)-\-{ab), and on the right a haploid mycelium {ab). The two mycelia are about 

 to come into contact with one another and to fuse with one another. In the 

 diploid mycelium (left) note the septa accompanied by clamp-connexions, the 

 narrow-angled mode of branching, the entire absence of oidiophores and oidia none 

 of which will be produced on it, and the presence in every cell of a pair of conjugate 

 nuclei. In the haploid mycelium (right) note the plain septa (without clamp- 

 connexions), the wide-angled mode of branching, and the isolated nuclei. In the 

 haploid mycelium oidiophores and oidia are absent only because the hyphae are 

 too young to produce them. 



The central hypha of the diploid mycelium {AB) + {ab) is growing toward, and 

 is about to come into contact with, a non-terminal cell of one of the hyphae of the 

 haploid mycelium {ab). 



Fig. 2. — The central hypha of the diploid mycelium has now come into contact 

 with a hypha of the haploid mycelium. A fusion at the point of contact is about 

 to take place. 



