256 INTRODUCTION TO THE STUDY OF FUNGI 



second generation of proniycelial spores, which in like manner 

 are cut off by a septum at the base, and become free inde- 

 pendent bodies. The act of conjugation, which results in their 

 production, is not an essential, because solitary primary spores 

 are equally capable of budding and producing secondary spores, 

 although tliey are usually smaller than those produced by con- 

 jugating primary spores. Hence it may be concluded that the 

 conjugation of the linear spores is not a sexual act. The 

 secondary spores are usually those which, by germination, enter 

 the host-plant and form a mycelium, but they are also capable 

 of budding and forming proniycelial spores of a third, or even 

 of a fourth, generation, if the conditions are unfiivourable for 

 infecting a new host-plant.^ 



The germination in Entyloma is similar to the above, but 

 less complex. The spores send out a germ -tube in about 

 twenty-four hours, and this constitutes the promycelium, which 

 develops several branches at the apex, each of which is cut 

 off by a septum at the base and becomes a proniycelial spore. 

 These spores then conjugate in pairs by the formation of a 

 connective bridge ; afterwards, by a continuation of growth at 

 the apex, secondary spores are produced, which fall off and 

 germinate. The growing point enters the host -plant and 

 forms a mycelium, which starts a new infection, and in com'se 

 of time teleutospores of a normal kind are developed in 

 clusters. In this genus conidia are also produced direct from 

 the mycelium, the conidia-bearers rising to the surface of the 

 leaf through the stomata. These conidia germinate on the 

 surface of the leaf upon which they fall, and the germ-tube 

 enters the stomata and forms a mycelium. They are able to 

 form secondary conidia, but this seldom takes place under 

 normal conditions. Hence there are two forms of reproduction 

 in this genus — that of the germinating teleutospores, forming a 

 promycelium which gives rise to proniycelial spores, and these 

 after conjugation developing secondary spores, capable of repro- 

 ducing the parasite, after an alternation of generations ; and, 

 secondly, of germinating conidia, which reproduce the parent 

 Entyloma at once, without an intervening generation. 



1 "On Bunt Spores," by M. C. Cooke, Journal of QuebcU Microscojncal Club, 

 vol. i. p. 167, 1868. 



