EXPERIMENTS WITH CRYPTOGAMIC GROWTHS. 



167 



paper; while, as originally shown by Mitzscherlich, (Pogg. Annal., 1855, p. 224,) and 

 again proved by the following experiments, yeast cells will not. Furthermore, none of the 

 above-mentioned bodies will pass through vegetable parchment, although fluids will. If, 

 then, upon adding a putrefying fluid to a saccharine solution, through the intervention of 

 filtering paper, we produce yeast and fermentation in that solution, while upon making the 

 addition through vegetable parchment we produce none, the method of the experiment 

 leaves no doubt that the yeast must have been developed from cryptogamic germs other 

 than yeast contained in the putrid matter. To carry out this plan of experiment, the fol 

 lowing apparatus was used: 



In a four or six-ounce glass beaker (not lipped) was placed a tube, made by cutting 

 off the bottom of a common test tube, three-fourths inch in diameter, and 

 as high as the beaker. This tube was open at the top, but closed at the 

 bottom by two layers of fine, strong filtering paper tied tightly over the 

 flaring end with waxed string, and rested on a fragment of glass rod placed 

 in the beaker; all these articles having been carefully washed, were put 

 together as described, and about two ounces of hot strong alcohol were 

 poured into both the tube and beaker. A piece of thin sheet-rubber was 

 next tied over the top, hermetically closing both beaker and tube, and the 

 whole apparatus, having been thoroughly shaken, so that the hot liquid 

 should come fully in contact with every part, was then set aside to cool 

 until wanted. 



The solution to be experimented on, which had been boiled, filtered, and then re- 

 boiled in a flask fitted up as an isolation apparatus, was in the mean time cooling in that 

 vessel. When this had cooled to about 85, the alcohol was removed from the apparatus 

 and the tube was rinsed with a little freshly-distilled water. Then one to two ounces of 

 the solution to be experimented on was placed in the beaker, while a little of the putre 

 fying or fermenting fluid was put in the inner tube. The sheet-rubber was finally stretched 

 tightly over all and tied as before, and the apparatus was then kept at a temperature of 

 75 Fahrenheit to 85 Fahrenheit in diffused daylight, (see plate, fig. 4.) 



The solutions used were of cane or grape sugar, mixed with extract of beef, or with 

 tartrate of ammonia and ashes of yeast. 



The following formulae gave the best results : 



A. 



Cane sugar 10 parts. 



Tourtelot s extract of beef 10 parts. 



Water 100 parts. 



B. 



Cane sugar - - - 1 P arts - 



Tartrate of ammonia 5 parts. 



Ashes of yeast 5 parts. 



Water 80 parts. 



