62 



INTRODUCTION TO THE STUDY OF FUNGI 



in the Phycomycetes two bodies are formed, or two specialised 

 cells come into contact, and the result is a zygospore, which is 



nearly always a resting spore, as a 

 consequence of fertilisation. In the 

 Discomycetes it is suggested that in its 

 earliest stage the elements of the 

 future cup, or receptacle, .become 

 fertilised by contact with specialised 

 filaments which represent antheridia. 

 In the Perisporiaceae special processes 

 are affirmed to be emitted from two 

 adjacent hyphae, which are supposed 

 to become respectively oocysts and 

 antheridia, and from their contact to 

 result in the production of fertilised 

 perithecia. In the whole of the 

 Basidiomycetes no definite mode of 

 fertilisation has been confirmed. 

 And for the rest, we seek for evidence 

 in vain. 



In Tilletia, a genus of the Ustilagineae, 1 peculiar phenomena 

 undoubtedly take place in the conjugation of promycelial spores, 

 but this can scarcely be interpreted as an act of fertilisation. 

 The facts are simply these : when the spore germinates it pro- 

 duces a promycelium, a germ tube, which gives origin to bodies 

 called primary sporidia, or, more properly, promycelial spores 

 (Fig. 40). "A very remarkable feature about these 'primary 

 sporidia ' is that they almost invariably conjugate in pairs ; that 

 is, adjacent pairs become organically united by a short tube grow- 

 ing from one and becoming blended with the other, thus placing 

 the protoplasm of the two sporidia in direct communication. 

 In some instances conjugation takes place before the primary 

 sporidia break away from the promycelium. After conjugation a 

 slender germ tube is formed, which receives all the protoplasm 

 from the two united sporidia, and if developed upon the proper 

 host plant, penetrates into its tissues and forms a mycelium, 

 which in turn produces a new crop of resting spores. In some 



Fig. 39. — Conjugating hyphae 

 in Bntomophthora. 



1 Monograph of British Uredineae and Ustilaginae, by C. B. Plowright, London 

 (1889), p. 88. 



