374 DIVISION III. MODE OF LIFE OF THE FUNGI. 



myself 1 and supplementing that of Vittadini 2 of Botrytis Bassii, the Fungus of the 

 ' muscardine ' of the silk-worm caterpillar which was formerly only known to produce 

 gonidia, that it might be thought that I had simply transferred the observations on 

 the one species to the other. The truth is that the two agree perfectly with one 

 another. 



Slight deviations from the course described in one species of insect occur in the 

 case of other species both in the reaction of the insect on the effects produced by 

 the parasite as well as in the development of the latter, as I have shown in another 

 place in connection with Botrytis Bassiana. A case of such deviation may be mentioned 

 here as occurring in Cordyceps. The caterpillars of Sphinx Euphorbiae when infected 

 with the ascospores were killed in from fifteen to twenty days, and the spots in the skin 

 infected by the Fungus showed, as in Botrytis Bassii, nothing beyond a brown discolo- 

 ration varying with the individual and spreading all round from the intruded hyphae. 

 The process was somewhat different when the caterpillars of Gastropacha Rubi 

 were infected. First of all it was much slower ; of seventeen specimens infected the 

 first died in about thirty days, the last not till after the lapse of seventy days, and 

 death was preceded by slowly increasing weakness. In the second place the skin 

 showed signs of disease in the spots where the spores had been sown after the Fungus 

 had penetrated into the live insect, but long before its death ; it swelled up and became 

 of a darker colour and hard, and was covered with a delicate white mould composed 

 partly of the regular verticillately branched gonidiophores of the species, partly of 

 accumulations of small roundish colourless cells and shortly cylindrical pieces of 

 hyphae divided by a few transverse walls. These hyphae not unfrequently abjointed 

 normal gonidia on narrowly conical lateral branchlets. It could not be determined 

 whether these structures were produced by the breaking up of mycelial hyphae or 

 by the development of normal gonidia. They showed themselves to belong to Cordyceps 

 by the fact that they all gave rise to mycelia with characteristic verticillately branched 

 gonidiophores when cultivated on microscopic slides. 



The above statements respecting the entrance of the Isaria farinosa-form into the 

 host are reproduced from my paper in the Botanische Zeitung for 1869, which should 

 be consulted for further details. In this paper and in that of 1867 I gave expression to 

 some doubts with respect to the view maintained by Tulasne 3 , that Isaria farinosa 

 belonged to the cycle of development of Cordyceps militaris ; these doubts were sug- 

 gested partly by the failure of attempts to obtain stromata and Isaria-forms in turn 

 from one another in specimens under cultivation, partly by differences, which it is true 

 were only quantitative, in the ramification of the branches producing gonidia. The 

 latter objection might easily be dismissed, and as has already been remarked in the text 

 I do not now think it necessary to maintain the first. A caterpillar of Sphinx Euphorbiae, 

 which had become a sclerotium as usual after infection by ascospores, when laid on moist 

 sand produced first of all two small stromata provided with normal perithecia. 

 These died before the asci were fully formed, and then Isaria was produced in 

 abundance. Portions of mycelium cultivated on microscopic slides had already 

 afforded Isaria. In this case therefore either Isaria was ultimately produced from 

 the ascospores, or the insect had been infected with them and unintentionally also 

 with Isaria, which in the end stifled and supplanted the form with perithecia. I have 

 no reason for assuming such accidental mingling of the two forms, and have framed my 

 opinion accordingly ; at the same time the possibility of the mixture is not excluded 

 and it was necessary to call attention to that fact. 



For some further remarks on Cordyceps, Botrytis Bassii and some other forms see 

 above, page 253. 



1 Bot. Ztg. 1867. 



3 Delia natura del Calcino o mal del segno (Giorn. Instit. Lombard. Ill (1852), p. 142, c. t. 2] 



3 Carpol. III. 



