134 



AFFINITIES OF PELLICULARIA. 



In the present number (pp. 116) we have briefly characterised and 

 described a new genus, and type species, of parasitic fungi, without 

 any detailed account of either, or the reasons which have led to 

 this step. The parasite in question is found on the under side of 

 coffee leaves, and is known to natives as " Koleroga," or " black 

 rot." It appears as an effused greyish-white patch or spot, often 

 covering half the under surface of the leaf. When moistened the 

 whole fungus may be removed by a knife, and strij^ped off like 

 a thin film of goldbeater's skin. It consists of an interwoven 

 layer of hyaline, branched, septate threads, on which are sealed, at 

 irregular intervals, globose, echinulate spores. The whole is in- 

 vested with a kind of gelatinous medium, which compacts it into 

 the above-mentioned film. The threads are from -005 to -0075 of 

 a millemetre in diameter, and the spores are about equal in diameter 

 to the threads on which they are borne. Owing to the investing 

 medium, it is exceedingly difficult to separate one thread from 

 another, or to obtain a free spore. By the use of a colouring 

 mediiim they can be discerned in situ, and sometimes a thread may 

 be disengaged so that the spores may be seen attached ; but this 

 is of rare occurrence. This constitutes a new form of Coffee 

 Disease. The principal scientific question which pi'csents itselT in 

 relation to this disease is the relationship and affinity of the fungus 

 which we have described. Two or three suggestions have already 

 been offered on the subject ; although made without any micro- 

 scopical examination of the plant itself, they are wo]»thy of a 

 passing notice. One suggestion is that the supposed fungus may be 

 an imperfect condition of some Lichen. It may be true that low 

 forms, or imperfect states, of Lichens are sometimes found on the 

 living leaves of growing plants ; yet the structure is hardly such as 

 those Lichenoid bodies assume. Considerable emphasis is some- 

 times placed on the presence of gonidia in the lichen thallus as 

 distinguishing it from fungi. There is no manifestation of such 

 bodies in the present instance, and it would be more satisfactory for 

 such an objection if a similar authentic instance could be adduced 

 of a destructive leaf-parasite, which is an undoubted Lichen. 

 Another suggestion has been offered, that it may be a low form of 

 Hymenomycetous fungi. If so, it should at least give some indi- 

 cation of its relationship. As spores are undoubtedly present, 

 there should also be basidia, bearing these spores in pairs or 

 quarternate ; at least, there should be some evidence of an 

 approach to such low Hj'menomycetal forms as Exohasidium or 

 Hymenula. Probably it was some such organism as Exohasidium 

 which was thought of when this suggestion was made, and, cei*- 

 tainly, we can observe no relationship whatever between them. 



The conclusion at which we have arrived, appears to us the most 

 tenable one, that the fungus in question belongs to the Hr/phomy- 



