scratching about for the truffles. There is a kind of race then between the mammal and the mycelium for the underground fungus. Botanists, who search for truffles always know where the Elaphomyces is to be found by looking for the spawn of the Torrubia on the moss. The spawn-covered moss points out the position of the truffle, as surely as the bird named the Great Honey Guide, Indicator major, Steph., leads hunters to bees' nests in Africa. A closely allied species of Torrubia, named T. militaris, Tul. (in the older books Cordiceps or Sphæria), of bright scarlet colour, is extremely common in Britain in the autumn and early winter, growing from dead pupa buried in the ground. The fungus resembles a scarlet club, about an inch or an inch and a half high. It grows in pastures and grassy places, where larvæ have buried themselves. The mycelium grows within the body of the pupa, and the scarlet club commonly grows from the first joint behind the head. The anatomical characters of T. militaris, Tul., agree generally with T. ophioglossoides, Tul. The Isaria disease possesses considerable interest on account of the popular belief that it is capable of greatly injuring, and indeed of killing the cattle that feed the grass infected with it. In September 1880 an instance upon occurred where two cows died in an Isaria-infected district from an affection of the lungs ; and when a postmortem examination was made it was found that the lungs were covered with a fungus-like growth, not unlike, it is said, the appearance presented by the throat in diphtheria. The veterinary surgeon who conducted the examination declared his opinion that the fatal ailment had been contracted from the Isaria-infected grass. The same medical practitioner is said to have fed two rabbits on infected grass only, and that they both died therefrom. It is, perhaps, unnecessary to say, that these cases are far from being proved. At the same time, it would not be wise to immediately say that such cases are impossible. In favour F of the doctor's view it may be called to mind that several members of the genus of fungi to which Isaria belongs, grow naturally on living animals. It is not usual for fungi to grow on living or, indeed, dead animal material, yet botanists are familiar with several such examples other than the ones already cited. The familiar fungus of the salmon disease, Saprolegnia ferax, Kutz., is one, and the white dusty fungus named Empusa musca, Cohn., so common on flies on our window panes in autumn, another. This is said by some observers to be merely a second condition of the Saprolegnia. The ringworm fungus Oidium porriginis, Mont., is another example; Microcera coccophila, Desm., a parasite of Cocci, -insects of the American blight class,-is a third; Onygena equina, Pers., which grows on the hoofs of dead horses, is a fourth, and the list might be greatly extended. Fries has described an Agaricus, named by him A. nauseosus, growing on the carcass of a wolf, and A. ostreatus, Jacq., has been seen in this country by Mr. C. B. Plowright growing on the dead body of a stranded whale; Onygena apus, B. and Br., is not uncommon on bones. These instances are not mentioned with the view of showing that Isaria fuciformis, B., is capable of killing cattle, but to indicate that other and, in some instances, closely allied fungi can support themselves on living and dead animal substances. It is extremely difficult to suggest any means for the destruction of the Isaria, partly because the fungus falls from the grass to the ground on the slightest touch, and partly because so very little is known of the fungus or its habits. The whole subject requires investigation. Some crops might be saved by removing the greater part of the grass before September, or by the substitution of some crop on which the Isaria could not grow. As humidity probably favours the growth of the pest, good and careful drainage might prevent its spreading. No doubt many insects carry the conidia, or spores, from place to place on their bodies, and so infect previously untainted districts. Towards the end of 1883 Mr. Greenwood Pim, M.A., F.L.S., and Dr. E. P. Wright, A.M., F.L.S., detected Isaria fuciformis, B., growing in a new position, viz. on grass belonging to a silo at the Albert Model Farm, Glasnevin, Co. Dublin. Mr. Pim kindly forwarded examples to us, and he soon afterwards published an illustrated account of the discovery in the Gardeners' Chronicle for 22d December 1883. Mr. Pim's examples were remarkable for being infested with a parasitic fungus, and one apparently till now undescribed. The parasite grows on the Isaria, breaks up its tissues, and more or less absorbs its crimson colour. The parasite is a Saprolegnia allied to S. ferax, Kutz., of the salmon disease, but different in many important characters. The new parasite, which may be termed Saprolegnia philomukes, W.Sm. (from sapros, decayed; legnon, a fringe or border; phileo, I love; and mukes, a fungus), is illustrated at Fig. 24, enlarged 400 diameters. The circular bodies are sporangia, zoosporangia, or spore-cases of unusually large size, and filled with small motile spores or zoospores. In the largest sporangium illustrated it will be seen that the zoospores are germinating within the sporangium, and protruding their germ tubes through its gelatinous wall. A remarkable character in this parasite is found in the septate or jointed mycelium, an unusual character in the Saprolegnieæ, in the mycelium carrying numerous conidia, as at AA, and in the sporangia and mycelial threads often becoming confluent, as at B, C. In the Dublin examples, the sporangia were so abundant that all parts of the Isaria threads were covered, they were so crowded together that they took pentagonal and hexagonal instead of circular forms. Many sporangia were sessile, or intercalated in the mycelium, whilst others were shortly stalked. Antheridia (male organs described under the fungus of the potato disease), as at D, were rare: the jointed my celium formed a dense transparent stratum over the host plant. In some places the parasite was colourless, like Parasite of Isaria fuciformis, B.; Saprolegnia philomukes, W.Sm. Enlarged 400 diameters. the better known species of Saprolegniea; in other places it was rose-coloured, from its absorbing the colour of the red Isaria. Saprolegnia philomukes, W.Sm., zoosporangia, very large, thick-walled, sessile, shortly stalked, or intercalated in the mycelium, sometimes confluent with each other, all bearing zoospores, which often germinate whilst still in situ. Antheridia elongated, rare; mycelium profusely septate, somewhat torulose, filled with colourless or rose-coloured protoplasm, and bearing many small abortive sporangia or conidia. We have seen a similar plant on fungi, with oospores as well as zoospores. |