252 M. C. COOKE ON BLACK MOULDS. 



nised. Recently having seen specimens of Kchweinitz's fungus, I 

 became satisfied that it was a good genus, although a supposed new 

 species which has been affiliated by an American botanist does not 

 belong to the same genus. From India came a second species, 

 which fully confirmed the judgment of Schweinitz, and not long 

 since Mr. Griffiths Morris, of Hereford, found a third species, the 

 finest and most imposing of all. In this latter the spores are very 

 much like those of Helminthosporium Smithii, but instead of being 

 simply borae on short erect threads, they are seated upon creeping 

 threads, as in the American and Indian species. There is evidently 

 an analogy between these three species and some of the long spored 

 species of Sporidesmium, but there is really no affinity. The Clas- 

 t< risporium might be characterised as a kind of Helminthosporium, 

 with creeping threads, but as the threads in Helminthosporium 

 should be erect, this is one justification of a distinct genus. 



There is yet another interesting genus of these fungi having close 

 relationship with the preceding, but differing in the character of the 

 threads, as well as a feature in spore production. This is Clado- 

 trichum. The black velvety patches of this mould on sticks and 

 twigs are just like those of Helminthosporium, but the threads, when 

 seen under the microscope, will be found to be swollen at the tips, 

 which assume the form of cups, or goblets ; whereas, these threads 

 are also gouty, and swollen several times throughout their length so 

 as to present a very singular appearance. A fine species of this 

 genus was figured by Corda in his " Prachtflora." There is an 

 additional distinction in this genus, and in Dendri/phium, that the 

 spores are produced end to end in a kind of chain at the tips of the 

 threads and their branches. It is by no means an easy feat to 

 accomplish to be able to see under the microscope spores so 

 attached. The attachment is so slight that the spores separate on 

 the least movement, and often only the basal spore can be seen 

 fixed to the thread. When the spores are not fully matured they 

 adhere more tenaciously, and then the structure may be seen indi- 

 cated in the juvenile spores. In all the species of Cladotrichvm 

 which I have seen, although the threads are rigid the membrane of 

 the spore is delicate, and, in drying, the extremities are liable to 

 collapse. 



Dendryphium is also a genus very similar to Helminthosporium, 

 but less robust, the patches are not dense and velvety, but thinly 

 scattered, and the spores, instead of being produced singly, are in 



