Licence: Public Domain Mark
Credit: The locust plague and its suppression / by Æneas Munro. Source: Wellcome Collection.
379/388 (page 355)
Licence: Public Domain Mark
Credit: The locust plague and its suppression / by Æneas Munro. Source: Wellcome Collection.
![also made on our locust with it. The results obtained were less satis- factory, however, than those with the native species. In the breeding cages, where all the conditions were under the control of the experimenter, the locusts exposed died. Outside no such favourable result followed its use. Just what this African fungus is has not been determined. It may be, and very likely is, quite another thing from both of the species referred to above. 895. Peculiarities of fungus growth.—“In the application of these fungus diseases it must be remembered that each fungus has its peculiar habits, and therefore requires certain conditions for its growth. If a cow or ox be attacked by a disease like ‘ tristeza] it does not neces- sarily follow that a sheep will also be subject to the same disease, though both are ruminants; just as like as not, the South African locust fungus gave the smallest results on Pachytylus migratorius, the most common of the destructive locusts in that region. To expect the fungus to take hold of and kill Schistocerca paranensis, which belongs to an entirely distinct sub-family of locusts, is hardly scientific, to say the least. That such results might occur is possible, but not probable. 896. Native species the most deadly to its hosts.—“ If any of these fungi are to be relied upon, ivhy not the native species, that is already acclimatised, and was discovered as an actual enemy of the very insect whose destruction is sought? Besides, the various species of Sporotrichum are recognised by both botanists and entomologists as the easiest of insect-attacking fungi to propagate and to preserve, besides being the most deadly in their effects on the hosts which they attack. 897. Fungi inoperative unless the climate favour.—“Experi- ments made during the past spring and early summer tend to show the inefficiency of this mode of locust-fighting to the exclusion of all others. Both at headquarters and at other points in the Republic careful lists were made of the different fungi mentioned, and with practically the same negative results, save where climatic conditions happened to be favourable at the time. But by always keeping a good supply of the fungus-killed locusts on hand, and using them where the opportunity occurs and the conditions are favourable, much good may and un- doubtedly will result.” 898. A logical fallacy.—There is much in the above quotation, referring to the South African locust fungus, that one would like an opportunity to thresh out; but, in passing, I might call attention to the mode of reasoning employed especially in one of the paragraphs (which for convenience I have put in italics). The reasoning partakes of a well-known fallacy in logic, and, though catching, is very erroneous. Let us bring it out. If a cow or ox be attacked in consequence of some known cause, then it is probable that any cow or ox, no matter](https://iiif.wellcomecollection.org/image/b28085917_0379.jp2/full/800%2C/0/default.jpg)
