X 



234 Atmospheric Life Germs. [April, 



he made use of such an infusion as the following ; that is to 

 say, a mixture of perfectly definite chemical substances : — 



Pure water ioo parts 



Sugar-candy 10 ,, 



Tartrate of ammonia . . o*2 to 0*5 part 



Ashes of yeast o"i part 



On impregnating such a liquid, when supplied with heated 

 air, with germs collected from the atmosphere, bacteria, 

 vibriones, and mucors, &c, were soon developed; the albu- 

 menoid and fatty matters, the essential oils, and pigments be- 

 longing to these organisms being derived from the elements 

 of the ammonia salt, the phosphates, and the sugar. These 

 complete organisms were built up out of the material afforded 

 by such a mixture of simple substances, a fact which is 

 quite contrary to Pouchet's declaration that ovules or germs 

 were evolved from a sort of vitality remaining in lifeless, or, 

 rather, dead, matter — that is to say, matter deprived of life. 



A solution consisting of — 



Pure water 100 parts 



Sugar-candy 10 ,, 



Tartrate of ammonia . . 0*2 to 0*5 part 



Yeast ashes o*i part 



Pure calcium carbonate . 3 to 5 parts 



showed much the same phenomenon, in fact, differing only 

 by a more marked tendency towards the changes called 

 lactic, viscous, and butyric fermentations ; and all ferments, 

 whether vegetable or animal, characteristic of these changes 

 were produced, simultaneously or successively. 



Prof. Tyndall, in 1870, gave us a means of investigation, 

 supplementary to the microscope, and of extreme delicacy. 

 Aided by Prof. Huxley, he proved that particles in a liquid, 

 quite invisible under an object-glass readily showing bodies 

 1^55 of an inch in diameter were revealed with the greatest 

 ease by means of a beam of light. If the air were pure, a 

 beam of sunlight travelling a darkened room would be in- 

 visible except where it struck upon the wall. It is the 

 scattering of the light by the floating dust which makes the 

 track luminous, the larger and more numerous the particles 

 the greater the luminosity. Hydrogen, coal-gas, air passed 

 through cotton-wool, and the air of still places, were found to 

 be free from floating matter. The writer, who has devoted 

 much attention to this subject since 1865, made use of this 

 discovery to aid him in a very careful repetition of some ex- 

 periments published by Dr. Bastian in " Nature " of June 



