ON THE STUDY OF MICRO-FUNGI. 367 



them. If this man were to try to arrange his library, he might 

 easily put the parts of a three volume work in different places in 

 his bookcase, instead of keejMng them together as one work, and 

 this is exactly what was done with these fungi, for many of them 

 were classified as being distinct species until their life histories 

 were studied, and it was shown that one species might have several 

 stages, and that, though the spores in each stage were different, 

 they required to be reckoned only as one species. 



If we briefly trace the growth of one of these fungi and follow 

 it through the different stages, we shall, perhaps, be enabled more 

 easily to understand what is here referred to, and for this purpose 

 we propose to take as a sort of typical example the species which 

 grows upon the Nipplewort {Lapsana communis). We have chosen 

 this species for our illustration because we have found it, in addi- 

 tion to being one of the commonest, to be one of the earliest to 

 appear after the winter is over, and because the host plant can so 

 readily be obtained for purposes of experiment by those who wish 

 to try to cultivate the fungus. If we were to examine one of these 

 plants which ultimately produces a fungus, we should at first see 

 no evidence of the presence of the fungus, although it had already 

 taken up a lodgment in the tissues of the plant ; but though 

 nothing is outwardly visible, the parasite is nevertheless gradually 

 gaining a footing. Within the tissues there is growing and deve- 

 loping that part of the fungus, the mycelium, which in due season 

 will make itself manifest and produce the spores which appear on 

 the surface of the leaf. This mycelium consists of an "assemblage 

 of hyaline tubes^ which ramify chiefly between the plant-cells, and 

 these mycelial tubes branch off and unite with one another until 

 a perfect network is formed within the tissues. 



When we remember that the fungus is a parasite, it is scarcely 

 necessary to say that consequently it lives at the expense of the 

 plant upon which it has taken up its abode, and it will at once be 

 evident to us that the mycelium is for the purpose of supplying 

 the fungus with the necessary nutrition by abstracting the material 

 which the plant has elaborated for its own use. The fungus 

 cannot, therefore, be considered as a very welcome guest, seeing 

 that the host must, nolens vole?is, provide it with sustenance quite 

 independent of any question of comfort or convenience. When 



