EXPLANATION OF PLATES IIV 



PLATES I AND II 



Figs, 1-12 in Plates I and II represent an attempt made by the author, in the 

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

 visualise diagrammatically in Coprinus lagopus the mode of union of two haploid 

 mycelia of opposite sex, (AB) and (ab), the production by these mycelia of 

 diploidised cells, and the development of one of the diploidised cells into a diploid 

 mycelium. 



Fig. 1. — Two haploid mycelia of opposite sex, (AB) on right (black nuclei) and 

 (ab) on the left (white nuclei), each derived from a single basidiospore (shown in 

 the lower left part of the diagram), are growing in close proximity and are about 

 to meet and fuse with one another. Note the simple septa (absence of clamp- 

 connexions), the wide-angled mode of branching, the oidiophores with their groups 

 of oidia, and the isolated nuclei. 



Fig. 2. — The middle hypha of the (ab) mycelium has grown toward, and has 

 come into contact with, the uppermost hypha of the (AB) mycelium. A fusion at 

 the point of contact is about to take place. 



Fig. 3. — Hyphal fusion between the two hyphae which were in contact has 

 just taken place by dissolution of the two appressed cell- walls. 



Fig. 4. — An (ab) nucleus has just moved toward the (AB) nucleus in the (AB) 

 half of the compound cell. Thus a pair of conjugate nuclei (AB) and (ab) has been 

 established, and the cell in which they lie may be said to have been diploidised. 



Fig. 5. — The diploidised hypha has grown apically in length, and the pair of 

 conjugate nuclei have advanced along it. They are about to divide conjugately, 

 and the conjugate division will be accompanied by the formation of a clamp - 

 connexion. 



Fig. 6. — In the diploidised hypha a backwardly directed hook has been formed. 



Fig. 7. — The (AB) nucleus has passed into the hook and is now alongside of the 

 (ab) nucleus which is in the main hypha. 



Fig. 8. — Conjugate division of the pair of conjugate nuclei (AB) and (ab) is 

 now taking place, and the two daughter pairs of conjugate nuclei will soon separate 

 from one another. 



Fig. 9. — The two daughter pairs of conjugate nuclei have now separated from 

 one another. The main hypha and the hook have each been divided by a septum. 

 The two nuclei of one pair of the daughter conjugate nuclei are now in the terminal 

 cell of the hypha, while the two nuclei of the other daughter pair are situated one 

 as a temporary prisoner in the hook-cell and the other in the subterminal cell of 

 the hypha. 



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