PSYCHE. 



[ January — Februarj' iSSS. 



meat from the tissues and the blood, ren- 

 dering the latter distinctly acid, as a 

 rule ; — and that death slowly supervenes* 

 After this event, these conidia elon- 

 gate, producing mycelial threads with 

 which the body soon becomes stiffened 

 and distended. Then they shoot up- 

 ward through the skin a forest of little 

 stems, fertile hyphae, which may 

 branch much or little, according to the 

 form, often covering the dead insect 

 with a microscropic pile like that of 

 velvet. From these hyphae other spore- 

 like bodies — spherical conidia — are 

 variously budded oft', borne on the stems 

 and branches singly, in heaps, in neck- 

 lace strings, forming finally a dense 

 powdery layer of cell-like particles, 

 white or greenish, often excessively deli- 

 cate and minute — in the silk-worm 

 species not more than 2 |a or 3 ^ in 

 diameter. Here the development may 

 stop — as it usually seems to do, indeed, 

 in the best known form, — the Botrytls 

 bassiana of the silkworm muscardine — 

 the conidia detached germinating else- 

 where, if they fall on favorable condi- 

 tions, and directly reproducing this 

 lowly vegetative stage. Under other 

 conditions — sometimes on other insects 

 — (the silkworm fungus on Gastropa- 

 cha rubi, for example) — the fertile 

 hyphae, instead of forming an infinites- 

 imal surface pile, spring up in strong 

 club-shaped tufts, bearing conidia on 

 their threads — this being the so-called 

 Isaria stage. Finally, the mycelium 

 within the dead body of the insect may 

 thicken, forming one or more compact 

 masses, from which a strong stipe may 

 spring up — like that from the mouth of 

 the white grub {Lachfiosterna f^iscd) , 



of which all have seen examples, or at 

 least illustrations — and at the end of 

 this stipe, immersed in a head more or 

 less distinct, another form of spores — 

 ascospores or thecaspores — may be 

 borne by a more complicated apparatus 

 of reproduction. This is the final repro- 

 ductive stage — the Cordyceps — best 

 illustrated b}' our Cordyceps vielol- 

 onthae* of the common white grubs. 

 These ascospores carry the fungus 

 species over winter ; but seem not 

 always necessary to this end, as the 

 spherical conidia of the Botrytis stage 

 of the silkworm muscardine have been 

 known to retain their vitality more than 

 a year. 



All these reproductive boxlles — asco- 

 spores and conidia — of Cordyceps^ 

 Botrytis^ and Isaria^ have germinated 

 freely again and again in sweetened 

 water, in sterilized beer-mash, in solu- 

 tions of gelatine and of gum, and may 

 even grow to some extent in pure water. 

 In these artificial cultures the Botrytis 

 stage arises, and may form its spheri- 

 cal conidia in vast abundance ; and these 

 have been used with perfect success for 

 the infection of healthy insects in great 

 variety. 



Perhaps the most notable of these 

 laboratory experiments have been made 

 by Tulasne, De Bary, and Elias Metsch- 

 nikofl^ — names of an authority so high 

 as to leave not the slightest doubt of the 

 correctness of their statements or the 

 soundness of their results. Excluding 

 the experiments of the older authors, 

 made when the existing knowledge of 

 these fungus species was probably insuf- 



* Saccardo, Sylloge fungorum, v. 2, p. 576. 



