h'f \ TinN. 545 



the spores of the little plant !' 1,1, illinin /// 



. 1 have all' rrcd, an- h-hi enough to lloat 



ill tin- air. A ml apple, a pea: . 



table marrow, or. a im-nt inn,-. I, an old n 



a dish of paste. >r a pot. of jam, constitute.- a ; 



for the /'fiiirillmiH. Now, if it could i dial the 



of dir air when .-own in this soil produces this plant, 



while, wanting the dust, neither du- air, nor tin- soil, nor 



both together can produce it. it would he ob\;< 



. in this eaae that the floating 4ntl oonUttot the 



germ- of PttUciMmm as that the pou n in \oiir 



^anli-n contained the germs of the plants which sprung 

 from them. 



But, how is the floating dust to be rendnv.l \i~ihlt-:' In 

 this way. Huild a little chamber and provide it with a 

 windows, and window-shutters. L--I an aperture he 

 made in one of the shutters through which a sunbeam can 

 pass. Close die door and windows so that no light shall 

 save through the hole in the shutter. The track of 

 the sunbeam is at first perfectly plain and vivid in the 

 air of the room. If all disturbance of the air of the 

 chamber be avoided, the luminous track will become 

 fainter and fainter, until at last it disappears absolute! y, 

 and i 1" the beam is to be seen. \Vh;i 1 the 



b'-am ' first? The iloating dust of the air, which, 



thus illuminated and observed, is as palpable to sense as 

 dust or powder placed on the palm of the hand. In the 

 still air thu dust gradually sinks to the lloor or sti< 



.alls and ceiling, until finally, by this self-cleansing 

 ir is entirely freed from iiicclmuicully sus- 

 pended matter. 



Thus far. 1 think, we have made our footing .^ure. Let 

 reed, ('hop up a beefsteak and allow it to remain 

 for two or three hours just cov.-n-d with warm u 



of the bc.-f in a concentrated form. 



By properly boiling the liquid and filtering it. \ou can 

 obtain from it a perfectly transparent beef-tea. xpoae a 

 number of vessels containing this tea to the mo'eless air of 

 your chamber: and expose a number of vessels containing 

 am.- liquid to the dust-laden air. In 



.ki*. and evimm.-d with the 

 one of them i- foiin-l j with the 



!' putrefaction. After three month.-. 



