On a New Species of Melanotaenium. Rudolph Beer. 341 



The spores are developed intercalarily upon the hyphac which 

 form the pseudo-parenchymatoiis masses. The youngest spores 

 observed measured 10 x 6/Lt in diameter (fig. 4). Spores at this 

 stage were seen to be unmistakably bi-nucleate and it was found 

 that the bi-nucleate condition was maintained in the spore until 

 quite shortly before maturity (fig. 7). The mature spore is uni- 

 nucleate (figs. 8 and 9), presumably through the fusion of the 

 two nuclei which exist during the earlier stages, but the actual 

 fusion was not observed. The single nucleus of the later stages 

 is, however, much larger in size than either of the nuclei which 

 occur in the bi-nucleate stage and this probably indicates that 

 it has arisen through the union of the two smaller nuclei. 



It may be mentioned here that spores in the most various 

 stages of development may occur close together within one 

 pseudo-parenchymatous mass of hyphae. Thus in fig. 3 a mature 

 spore containing a single nucleus occurs side by side with a 

 much younger one which is still bi-nucleate. 



The spore-membrane itself is apparently single and no success 

 was obtained in attempting to demonstrate any lamination in 

 it or in revealing the presence of an endospore in any of the 

 spores which were examined*. 



It will be seen from this brief account that the mature spore 

 of Melanotaenium is uni-nucleate whilst the hyphal cells and 

 the young spores are bi-nucleate. As germination of the spores 

 of M. Lamii was not obtained it is not possible to say definitely 

 where the transition between the uni-nucleate and the bi-nu- 

 cleate stages occurs, but it may be pointed out that Woronin 

 (1881) in his study of M. endogenum observed numerous cases 

 of the germination of the spores and found the conidia con- 

 jugating with one another. It is not improbable that this is the 

 point in the life history of the fungus at which, by the passage 

 of the nucleus from one conidium to the other, it attains the 

 bi-nucleate condition. 



I should like here to express my great indebtedness to Miss 

 Wakefield for her kind assistance throughout in the preparation 

 of this paper. 



BIBLIOGRAPHY. 



de Bary, A. — Protomyces macrosporus u. seine Verwandten. 



(Bot. Zeit. Bd. xxxii, p. 105, 1874.) 

 Beck, G. — Plantae Novae. (Oesterreich Bot. Zeit. Bd. xxxi, 



p. 31. 1881.) 

 Cooke, M. C. — British Fungi. (Grevillea, No. i, p. 7, 1872.) 



* Osner (1916) found that the spores of Ustilago striaeformis (West.) Niessl. 

 possessed a double spore coat, a thick, dark exospore and a hyaUne endospore. 



