CYSTOPUS, OR WHITE RUST. 147 



The conclusion arrived at by De Bary, and supported by other 

 observers, is to the effect that as we proceed along the main lines 

 from the lower to the higher Fungi, the sexual process and sexual 

 organs gradually become less and less evident, and at length 

 disappear altogether, and the fructification then arises by apogamy. 



We are indebted to Marshall Ward for some very ingenious 

 suggestions on this subject. He points out that the absence or 

 presence of sexual organs rises or falls with the nature of the 

 parasitism or saprophytism displayed. In the Saproleg?iiece, for 

 instance, the Fungi may probably be looked upon as very highly 

 nourished by the decomposing proteids of animals. Their sexual 

 organs seem to be present in most cases, but functionless. 



In the Zygomycetes^ which are essentially saprophytes on 

 decaying vegetable matter, etc., or parasitic on one another, and 

 may be probably regarded as not so highly nourished, we find the 

 sexual organs functionally perfect, though very simple in charac- 

 ter. In the UstilaginecB we meet with parasitism of a peculiarly 

 high order, so to speak. The fungus not only robs its host, but 

 has in most cases curiously adapted its life to the habits of the 

 latter, using it rather as a slave than as a victim to be destroyed 

 forthwith. The same is true for the highly-organised Uredinece, 

 and we here meet with the highest adaptation of all — heteroecism. 

 But in both these groups the search for sexual organs has hitherto 

 proved futile. 



Again, if we proceed upwards from the E?ysiphece, whicli 

 are epiphytes, adapting themselves to parasitic habits of that 

 special kind, which leads to life in the interior of temporary 

 organs like leaves, through the Ascouiycetes we find, speaking 

 generally, more and more tendency towards close and specially- 

 adapted parasitism, ending in the parasitic Fezizas, forms like the 

 F/eosporas, etc., and especially Claviceps. There is thus strong 

 reason for believino; that a connection exists between the mode of 

 life of a given Fungus, and the extent to which it is apogamous. 

 We are at least assured that profound differences exist — in degree 

 at any rate — between the saprophytism of a mucor growing in 

 a solution of horse-dung, and of a FytJiium developing its 

 fructification in the rotting parenchyma of a plant which it has 

 previously killed. There is also an equally striking difference 



