ON THE SEXUALITY OF THE EUNGI. 309 



he most serious objections to the above hypothesis will 

 probably occur to those who draw conclusions from the life- 

 history of imperfectly known forms. Without wishing to 

 disarm any criticism whatever, I would mention two points to 

 be borne in mind in this connection. 



Many Fungi are known to be capable of adapting them- 

 selves to widely different modes of life, and it is extremely 

 difficult to say how far they are parasitic or saprophytic. 

 Leaving the Bacteria alone, I need only mention Koch's 

 experiments with species of Mucor and Aspergillus, and 

 Eidam^s observations on Sterigmatocystis :^ these Fungi 

 were found to be pathogenic to a disastrous extent when 

 injected into the blood-vessels of living animals. Again, 

 Kihlmann's brilliant research on Melanospora, embodied in 

 an earlier portion of this essay, brings to light an extraordi- 

 nary case of parasitism and adaptation. 



Secondly, we really know very little of the mode of life of 

 many Fungi in their earlier stages; we assume, rather than 

 know, that many forms of Pyrenomycetes, for instance, are 

 saprophytes. However, less is to be gained by dwelling upon 

 these doubtful matters than by courting criticism of the main 

 point at issue. 



I may say, in conclusion, that it was during the study of the 

 parasitic fungus of the CoflFee disease (Hemileia vastatrix) 

 in Ceylon that I was first led to speculate on the enormous 

 amount of energy displayed by an organism which shows not 

 the remotest satisfactory trace of sexuality, but which repro- 

 duces itself through many generations exclusively by means of 

 asexual spores. That this energy of reproduction is derived 

 from the Coffee tree there can be no doubt, and that it is at 

 the cost of the reproduction of the host is sadly evident ; the 

 clear inference from the fact that the Coffee leaf supplies sub- 

 stance for the reproduction, &c., of a Fungus at the expense of 

 its own fruit, is that the Fungus takes matters which are very- 

 rich in energy, so rich, indeed, that the Fungus is not neces- 



1 Colm's • Beitiage,' B. iii, H. iii, pp. 397 ff. 

 VOL. XXIV. .NEW SER. X 



