ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 295 



marked peculiarities were manifested in the cultures with a zinc salt 

 together with potassium chloride. When these were compared with 

 cultures in which potassium chloride only was used, the influence of 

 the zinc salt was very evident. The habit of the culture with sodium 

 chloride also differed from that with potassium cliloride. 



With regard to Nageli's statement that potassium is not absolutely 

 essential to the growth of fungi, but that it may be replaced by 

 rubidium or ceesium, the author found this to be true as respects 

 rubidium, while with caesium or lithium not the least trace of develop- 

 ment was observed. 



A final series of experiments was undertaken with nutrient fluids 

 containing equal quantities of organic substances, phosphoric acid, 

 and potassium chloride, but with different alkaline salts, viz. sulphates 

 of magnesium, calcium, and strontium. Only in the first of these did 

 a good pellicle develope ; the rest manifested no development at all. 

 The absence of calcium, so important in the nourishment of green 

 plants, appears to be of no consequence to that of Mycoderma. 



Origin of Microzymes and Vibrios of Air, Water, and Soil. — 

 E. Duclaux * has experimented on plants grown in soil free from 

 microbes in order to determine the effect of their presence upon 

 germination. He used peas and Dutch beans, the cotyledons of 

 which uniformly appear, one below the soil, the other above. The 

 soil had been previously sterilized and moistened with sterilized 

 milk. Under these conditions, germination did not take place, and 

 at the end of two months the milk showed no indication of alteration. 

 These experiments tend to prove that the presence in the soil of 

 microbes is necessary to the development and life of plants. 



M. Pasteur mentioned when the paper was read that he had 

 proposed to his pupils to examine the effect of feeding an animal 

 from birth with food the elements of which had previously been 

 freed from microbes, and consequently reduced to its nutritive prin- 

 ciples, pure and simple. To this he had been led by the idea that 

 in such conditions the maintenance of life and development would 

 be impossible, leading to the important suggestion that the presence 

 of microbes in food is necessary for digestion. The absence of 

 microbes renders impossible the accomplishment of the actions 

 necessary for the elaboration of the matters destined to serve for 

 nutrition. The importance of an exact knowledge of the part played 

 by microbes in digestion cannot be overrated. 



A. Bechamp,f after a reference to the previous communication of 

 M. Duclaux, points out that the question at issue may be stated in these 

 terms : Have the microzymes and vibrios of the atmosphere been 

 primitively disseminated in the air, and thence fallen on the ground 

 to penetrate into its depths and waters, as Pasteur thinks ; or are not 

 the latter, as the author thinks, the origin of what are found in the 

 atmosphere? M. Bechamp maintains that primitively there were no 



* Comptes Rendus, c. (1885) pp. 66-8. 

 t Ibid., pp. 181-4. 



