PROTOPHYTIC AND OTHER FUNGI. 313: 



envelope is formed, in which the spores lie irregularly imbedded, con- 

 tinuing to multiply by subdivision, so as to form large irregular masses. 

 The development of the spore into a filament commences by the putting 

 forth of a small curved prolongation, which gives it the shape of a 

 comma ; and as every possible gradation in size and form is seen between 

 the smallest comma and the largest filament, there can be no reasonable 

 doubt of the development of the former into the latter. Granular 

 spheres are also seen, which may consist, like those of Bacillus, of 

 minute particles emitted from the spores, and capable of development 

 into a new generation of Spirilla. 



309. Of the whole of this group it may be remarked that, so far as is- 

 yet known, they multiply either by transverse cell-division, or by the 

 breaking up of their endoplasm into spores, the production of which is 

 entirely non-sexual. Nothing like 'conjugation,' or any other form of 

 sexual Generation, has yet been witnessed in any of them; and until such 

 shall have been discovered, no confidence can be felt that we know the 

 entire life history of any one type. 1 It is a fact of great importance in 

 the physiology of the Schizomycetes, that, in certain stages of their lives, 

 they can resist both very high and very low temperatures without the 

 loss of their vitality. In the active state of Bacteria, etc., they appear 

 from the experiments of Dr. Eidam (which were conducted under the 

 superintendence of Prof. Cohn) to be killed by continuous exposure to a 

 temperature of 124 for three hours, or to 115 for thirteen or fourteen 

 hours, although capable of sustaining a temperature of 120 for a short 

 time wi thout losing their vitality. But in the Micrococcus-stage, although 

 killed by being boiled for a few minutes, they can sustain exposure to a- 

 dry heat of 230 Fahr., but are killed by being heated to 248. 2 And 

 this is probably the explanation of the fact, that Prof. Tyndall found 

 that he could not sterilize an infusion of old hay (the Bacteria germs 

 contained in which may be supposed to have had peculiarly dry hard 

 envelopes) without boiling it continuously for several hours; though 

 repeated short boilings with intervals of cooling would effectually destroy 

 their power of germinating. 3 Even severe cold does not destroy the 

 vitality of Bacteria and Bacilli in their ordinary condition, although it. 

 suspends their activity; for Bacteria have been found to recover them- 

 selves completely after exposure to a temperature of Fahr. ; and the= 

 spores of Bacillus antliracis have recovered their germinal power after 

 exposure for several hours to a temperature averaging 8 below the zero 

 of Fahrenheit. 



310. When these facts are allowed their due weight, no difficulty 

 ought to be felt in admitting the action of Bacteria, etc., in producing 

 decomposition, under conditions which might at first view be fairly sup- 

 posed to preclude the possibility of their presence. This action is 

 altogether analogous to that of the Yeast-plant ( 311) in producing 

 saccharine 'fermentation; and the careful and exact experiments of 

 Pasteur, 4 repeated and verified in a great variety of modes by Professors. 



1 As it seems unquestionable that among the higher Fungi ' conjugation ' often 

 takes place at a very early stage of growth, it seems a not improbable surmise 

 that the 'granular spheres' observed by Mr. Ewart in Bacillus and Spirillum, 

 which seem to correspond with the 'microplasts' observed by Prof. E. Ray 

 Lankester in his Bacterium rubescens, may be a product of conjugation in the 

 Micrococcus-stage of these organisms. 



2 " Beitrage zur Biologic der Pflanzen," Heft 3 (1875). 



3 " Philosophical Transactions," 1877, p. 183. 



4 The experiments which have always seemed to the Author most satisfactory,. 



