351 FUNGI INHABITING THE ANIMAL BODY. 



having been generally found to exist in the cases in which the plant 

 has been most abundant) , than to be itself the occasion of the disease, 

 as some have supposed. The Sarcina presents itself in the form of 

 clusters of adherent cells arranged in squares, each square contain- 

 ing from 4 to 64, and the number of cells being obviously multi- 

 plied by duplicative subdivision in directions transverse to each 

 other. In fact, its general mode of growth would indicate a near 

 relation to Oonium, one of the Volvocinese, which presents itself in 

 similar quadripartite aggregations ; and many Botanists, looking 

 to this circumstance, and to the residence of the plant in liquid, 

 regard it as belonging to the group of Algse. It agrees with the 

 Fungi, however, in not living elsewhere than in liquids containing 

 organic matter ; and there can be little doubt that as no fructifica- 

 tion has yet been seen in it, only its earlier and simpler condition 

 is yet known to us. Its true place cannot be determined until its 

 whole life -history shall have been followed out. 



265. There is a form of Fungous vegetation that is prone to 

 develope itself within the living body, which is of great economic 

 importance as well as of scientific interest ; this is the Botrytis 

 bassiana (Fig. 167), a kind of 'mould,' the growth of which is 

 the real source of the disease termed Muscardine, that sometimes 

 carries off Silk -worms in large numbers, just when they are about 

 to enter the chrysalis state, to the great injury of their breeders. 

 The plant presents itself under a considerable variety of forms 

 (a-p), all of which, however, are of extremely simple structure, 

 consisting of elongated or rounded cells, connected in necklace- 

 like filaments, very nearly as in the ordinary ' bead-moulds. ' The 

 sporules of this fungus, floating in the air, enter the breathing 

 pores which open into the Tracheal system of the Silkworm' (§ 524): 

 they first develope themselves within the air-tubes, which are soon 

 blocked up by their growth; and they then extend themselves 

 through the fatty mass beneath the skin, occasioning the destruc- 

 tion of this tissue, which is very important as a reservoir of nutri- 

 ment to the animal when it is about to pass into a state of complete 

 inactivity. The disease invariably occasions the death of the silk- 

 worm which it attacks ; but it seldom shows itself externally until 

 afterwards, when it rapidly shoots forth from beneath the skin, 

 especially at the junction of the rings of the body. Although it 

 spontaneously attacks only the larva, yet it may be communicated 

 by inoculation to the Chrysalis and the Moth, as well as to the 

 worm ; and it has been also observed to attack other Lepidopterous 

 Insects. A careful investigation of the circumstances which 

 favour the development of this disease was made by Audouin, who 

 first discovered its real nature ; and he showed that its spread is 

 favoured by the overcrowding of the worms in the breeding estab- 

 lishments, and particularly by the practice of throwing the bodies 

 of such as die into a heap in the immediate neighbourhood of the 

 living worms : this heap speedily becomes covered with this kind 



