224 FUNGI. 



are accompanied by fungi, which either completely destroy the 

 tissue, or alter its nature so much by the abstraction of the 

 cellulose and lignine, that it becomes loose and friable. Thus 

 fungi induce the rapid destruction of decaying wood. These 

 are the conclusions determined by Schacht, in his memoir on 

 the subject.* 



We may allude, in passing, to another phase of destructive- 

 ness in the mycelium of fungi, which traverse the soil and in- 

 terfere most injuriously with the growth of shrubs and trees. 

 The reader of journals devoted to horticulture will not fail to 

 notice the constant appeals for advice to stop the work of fungi 

 in the soil, which sometimes threatens vines, at others conifers, 

 and at others rhododendrons. Dead leaves, and other vegetable 

 substances, not thoroughly and completely decayed, are almost 

 sure to introduce this unwelcome element. 



Living plants suffer considerably from the predations of para- 

 sitic species, and foremost amongst these in importance are 

 those which attack the cereals. The corn mildew and its accom- 

 panying rust are cosmopolitan, as far as we know, wherever 

 corn is cultivated, whether in Australia or on the slopes of the 

 Himalayas. The same may also be said of smut, for ~Ustilago is 

 as common in Asia and America as in Europe. We have seen it 

 on numerous grasses as well as on barley from the Punjab, and 

 a species different from Ustilago maydis on the male florets of 

 maize from the same locality. In addition to this, we learn 

 that in 1870 one form made its appearance on rice. It was 

 described as constituting in some of the infested grains a 

 whitish, gummy, interlaced, ill-defined, thread-like mycelium, 

 growing at the expense of the tissues of the affected organs, 

 and at last becoming converted into a more or less coherent 

 mass of spores, of a dirty green colour, on the exterior of the 

 deformed grains. Beneath the outer coating the aggregated 

 spores are of a bright orange red ; the central portion has a vesi- 

 cular appearance, and is white in colour.f It is difficult to 



* Schacht, " Fungous Threads in the Cells of Plants," in Pringsheim's " Jahr- 

 buch." Berlin, 1863. 



t " Proceedings of the Agri. Hort. Soc. of India" (1871), p. 85. 



