24 NATURE OF THE SPERMATIA 



circumstances, would shew quick and luxuriant growth : tln-v 

 cannot be degenerate conidia, because the nucleus is large and 

 well-formed though at times no nucleolus can be seen. 



(5) They are sometimes accompanied by a sweet fluid, 

 which gives off a pleasant, or more rarely an unpleasant, smell, 

 as in P. suaveolens (obtegens). Uromyces Pisi, Cronartium Quer- 

 chs, etc. It is said that, in Japan, children lick the abundant 

 spermogones of C. Quercus on account of the sweet juice that 

 oozes from them. The presence of this can be readily under- 

 stood, if the aid of insects is invoked as well as wind, in order 

 to carry the passive spermatia to the trichogyne projecting 

 through a stoma, but otherwise is without explanation. The 

 larva of a fly (Diplosis) or a similar organism, is to be found 

 crawling about the leaf and feeding on the spermatia and aecidio- 

 spores of many Uredinales; its body is quite orange in colour 

 through being filled with them, and the spermatia would adhere 

 to its outer surface. Though the spermogones of P. Caricis are 

 usually on the opposite leaf-surface to the aecidia, yet in very 

 many species they occur intermixed, and not infrequently 

 the secidia grow habitually in circles round little groups of 

 spermogones; a remarkable instance is seen in Phragmidium 

 Rubi-idaei (=P. gracilei : see Fig. 225. 



(6) The most likely theory of the evolution of the Uredinales 

 is that which places the majority of the micro- (including the 

 lepto-) forms as the most recent. 



It is just in these, and in no others, that the spermogones 

 are least often to be met with (see p. 39), as w T ould be expected 

 if they are furthest in descent from the primitive forms in 

 which a true act of fertilisation occurred. 



(7) If, on the other hand, we look upon the spermatia as 

 conidial forms, i.e. as merely an additional means of vegetative 

 multiplication, we are confronted by this difficulty (as well as 

 those referred to above) that they appear just at that period of 

 development at which they are least wanted, whilst they are 

 missing in many micro-forms where additional help would be 

 most welcome. The ascidiospores have been shown in many 

 ways to possess an unusual amount of vigour and to be able to 

 produce a stronger infection than the uredospores, which stand 



