6l2 



THE POPULAR SCIENCE MONTHLY. 



Fig. 22 

 a Cult 



The great abundance of germs in the air is well shown in attempt- 

 ing to obtain pure cultures of the ferments, as all the care and some 

 of the methods of the pathogenic bacteriologist must be practiced. 

 The fact of their universal presence is more readily demonstrated by 



growing them than can be done by the microscope 

 alone, as one germ soon grows to a great colony, and 

 to be seen singly may require staining to be differen- 

 tiated by the microscope, so that it is likely it would 

 have been overlooked in a specimen directly from the 

 wood. The general dissemination of the spores of 

 the fungi of the highest types by the wind has been 

 mentioned ; their invisibility like that of the fer- 

 ments, however, eludes ordinary observation, and the 

 bountiful supply of each, on every stick of timber, or 

 the smallest piece of wood, is unnoticed. 



Fig. 23 shows the spores of Goprirvus atramen- 

 tarins (Fr.), " Inky Coprinus," magnified one hun- 

 dred diameters, which just enables the engraver to 

 define their form. Many spores are much smaller 

 Inoculating and of different shapes, while the ferments found in 

 the hemlock require enlarging to one thousand di- 

 ameters to be as distinctly seen ; what the latter lack in size is made 

 up in quantity ; and this it is which enables them to set up such 

 destructive fermentations. 



When decayed timber and ties dry, and crumble to dust, some of 

 the ferments which caused their destruction will be disseminated by 



the winds, and each one can form a colony ; not a stick 

 of timber in the vicinity will escape a supply ; drying 

 at ordinary temperatures does not destroy, but only 

 renders them inactive for the time being, and harm- 

 less until surrounded by the proper conditions for their 

 germination. When these ferments fall upon unsea- 

 soned wood which contains from thirty-five to fifty per 

 cent of its weight of moisture, many of them germinate and set up 

 fermentations, especially in the sap-wood, increasing their number, 

 though their further growth may be eventually checked by seasoning ; 

 the wood, however, shows the effect in proportion to the extent of 

 the fermentations. 



The molds play an important part, and are often associated in the 

 decomposition of the sap or fluids in the sap-wood, extending to those 

 of the hearjt-wood. 



The cellulose which composes the principal part of the cell- walls of 

 the various tissues in the wood is of itself quite indestructible, and 

 requires some inducing cause to start its decomposition through the 

 contained sap or moisture, which the fungi can do when warmth and 

 air, the latter in limited quantity, are present for them to grow. 



Fig. 25, ia. 



