Organic Ferments. 213 



change of habit, and a loss of an important organ and an important 

 function, could pass from a vegetable to an animal mode of life; in 

 short, how the animal kingdom has been derived and developed from 

 the vegetable kingdom. 



The Myxomycetes, or slime moulds, are masses of naked vegetable 

 protoplasm. They may be obtained on the surfaces of decayed logs, 

 leaves and other vegetable matter, or on grass, &c. , near decaying veg- 

 etation. They are subject to movements called streaming, in which 

 currents are observed to run in one direction awhile, then to reverse and 

 run back. Sometimes this movement, by being more forcible in one 

 direction than the other, results in slowly conveying the whole mass 

 bodily. 



These slime moulds, according to Prof. Bessey, are the counterparts of 

 the Monera. He says it is not improbable ' ' that in the Myxomycetes 

 we have the terrestrial phase, and in the Monera the aquatic phase of a 

 common group of organisms. The two are alike in structure and proba- 

 bly also in their affinities, and all the difference between them may, 

 with probability, be referred to the difference of habit, the terrestrial of 

 the Monera and the aquatic of the Myxomycetes. (Bessey's Botany, 

 p. 207.) The slime mould being destitute of chlorophyl, although it is 

 only vegetable protoplasm, cannot be distinguished from the animal 

 Moneron, and the animal and vegetable kingdoms here occupy the same 

 ground. The Protomyxa is an organism formed from this protoplasm, 

 which, passing through several stages of development, returns again to 

 protoplasm. (See Chap. 33.) 



CHAPTER XXVII. 



ORGANIC FERMENTS. 



Beer yeast or alcoholic ferment is a minute, single cell organism 

 which will live and grow in a variety of solutions. It is called Saccharo- 

 myces Cerevisice, literally, sugar mushroom of beer. 



Brewers use two varieties of yeast in brewing beer. One is the surface 

 variety and the other the sedimentary. 



In the process of "working," the former comes to the top and the 

 latter settles to the bottom. The temperature required is from 53 to 

 65 Fahrenheit, the surface variety requiring the highest temperature. 

 The surface variety is also the more active; fermentation, when it is 

 used, requiring but two or three days, while with the sedimentary kind 

 it takes from eight to ten days. The increase of the yeast during the 

 process is seven or eight fold. After the sedimentary fermentation the 

 yeast found at the bottom of the vat is composed almost entirely of cells of a 



