62 M. C. COOKE ON MICROSCOPIC MOULDS. 



We pass now from the true moulds, which are usually white or 

 coloured, as seen in patches by the naked eye, to those which are 

 always found in more or less black patches, and hence have come 

 to be called " Black Moulds." These are not generally so delicate, 

 the threads are more rigid, and the spores are often more firmly 

 attached. They are found on herbaceous stems, bark, rotten wood, 

 and in fact in a great variety of localities. One of the largest 

 genera, that of Helminthosporium, and one of its commonest and 

 finest species, will furnish our first illustration. 



Wherever holly bushes are at all plentiful, twigs and branches 

 cut down to stop gaps in the hedges, or that have lain on the 

 ground during winter will usually be freely covered with sooty 

 patches, variable in form and size, but looking just like patches of 

 soot, from the size of a large pin's head to some inches in length. 

 A portion of one of these patches will not make such a neat object 

 or such an attractive one as the majority of true moulds, or even 

 many of the Black Moulds, but it is always advisable to commence 

 an examination with a two-inch or one-inch power. 



This Holly Mould will be observed to consist of erect simple 

 threads, bearing spores as long as themselves. The threads are 

 nearly opaque, of a dark brown, paler above and more translucent, 

 jointed and erect. But the spores are the most prominent feature. 

 Often longer than the threads themselves, and at first borne on 

 their apices, they are of a beautiful clear brown, nearly cylindrical, 

 a little attenuated towards each end, or sometimes club-shaped. 

 Throughout their whole length these spores are divided by 

 numerous septa into a number of cells, the largest in any 

 species of the genus with which I am acquainted. The name of 

 this fungus is Helminthosporium Smithii. (PL vii.) It is dedicated 

 to the immortal Smiths, so that the name of Smith may not be 

 forgotten. Had it been called magna or gigaspora it would doubt- 

 less have been far more appropriate, but such vulgar notions of 

 propriety do not always hover around naturalists when they name 

 a new species. It is a strange infatuation which besets some men 

 thus to immortalise the Smiths. I remember one botanist who 

 made a poor fellow's name do duty, as a specific name, for twenty 

 or thirty new species of plants. But it wasn't Smith. 



Dead wood, rotten sticks, dead stems of herbaceous plants, and 

 dead grasses will furnish other species of the same genus. Most 

 of them so nearly alike in the appearance that they present to 



