NATURAL HISTORY SOCIETY OF GLASGOW. 207 



(4) The fact that fungi can usually flourish as toell in darkness 

 as in sunlight gives them a further advantage in regard to their 

 nefarious habits. The absence of light seems in many cases to be 

 rather conducive to their development, as they are generally most 

 abundant in dark cellars, hollow trees, under logs, or in the 

 obscurity of woods, while some are subterranean. Not a few of 

 them seem, however, to require light for particular processes in 

 their growth and reproduction. 



(5) The varied modes of reproduction and the alternation of 

 generations, so common in the loiver forms, give them a further 

 advantage in the struggle for life. If Peronosj)ora infestans, for 

 example, were limited to the production of "resting spores," it is 

 evident that the havoc it occasions would be much reduced; but by 

 the ready production of conidia and zoospores it propagates its 

 kind with great rapidity and success. The alternation of genera- 

 tions in which, for instance, the forms known as Aecidium, Uredo, 

 Puccinia, and again Aecidium, are successively produced, seems to 

 serve the same purpose. 



There are, without doubt, other points in connection with the 

 reproduction of fungi which may yet be found to be of importance 

 in relation to their extensive diffusion and modes of nutrition; but 

 considerable obscurity still rests on many of these processes. For 

 instance, little of a satisfactory nature is known as to the function 

 of the spermogoues and their sperm atia, which are found in not a 

 few of the Coniomycetes. 



In proceeding to consider shortly the phanerogamic parasites 

 and saprophytes, my remarks will be chiefly confined to the plants 

 found in Britain. Probably all plants with viscid hairs or 

 glutinous excretions retain and absorb the nitrogenous organic 

 matter floating in the air, and in some cases living insects as well. 

 That glandular hairs have the power of absorbing ammonia, both 

 in solution and in the gaseous state, has been clearly proved by 

 the experiments of Dr. Darwin. As there is an appreciable 

 quantity of ammonia both in the atmosphere and in rain-water, and 

 as many plants bear individually an immense number of glandular 

 hairs, this mode of nutrition may not be so unimportant as we 

 might at first be inclined to suppose. Darwin states that a plant 

 of Primula sinensis was found to bear upwards of 2,500,000 of 

 these glandular hairs. He is further of opinion that such plants 

 obtain animal matter from the insects entangled by the viscid 



