PKOGRESS OF MICROSCOPICAL SCIENCE. 25 



quantity of glycerin extract of pepsin in water acidulated with hydro- 

 chloric acid. The liquid so obtained is first rendered alkaline by the 

 addition of liquor sodas, then slightly acidulated with acetic acid and 

 boiled. The syntonin thus precipitated is separated by infiltration 

 from the clear liquid, which is then evaporated to a syrup and poured 

 in a thin stream into strong alcohol, with constant agitation. The 

 precipitated peptone is separated after some hours and washed with 

 alcohol, and redissolved in a small quantity of water. The solution 

 is again precipitated by pouring it into alcohol in the same way as 

 before, and the precipitate washed and dried. 



Flasks having been half filled with the liquid thus prepared (in 

 1000, 2 each of nitre and Epsom salts, a trace of phosphate of lime, 

 25 parts of grape sugar, and 4 parts of peptone), each is boiled for 

 ten minutes, closed, while boiling, with the earthenware plate as above 

 described, and placed as soon as it is cool in the warm chamber at 

 30° C. The experiment so made " gave, without any exception, a 

 positive result in every case. After two or three days the fluid was 

 crowded with actively moving Bacterium termo." 



The readers of 'Nature' are aware that in June last Dr. Sanderson 

 published a repetition of Dr. Bastian's experiments with a variation 

 not of the liquid but of the mode of heating.* Instead of boiling the 

 flasks for ten minutes over the open flame and closing them in ebulli- 

 tion, he boiled them, closed them hermetically, and then placed them 

 in a digester in which they were subjected to ebullition under a pres- 

 sure of two inches or more of mercury. The result was negative. 

 There was no development of bacteria. 



Since the publication of his experiments Huizinga's have appeared. 

 His results, regarded as a proof of spontaneous generation, is clearly 

 not superior to Bastian's. The substitution of a soluble immediate 

 principle for an insoluble mixed product like cheese, and the use of a 

 definite solution of sugar and salts, are not material improvements. 

 The question is not whether the germinal matter of bacteria is 

 present, but whether it is destroyed by the process of heating. Con- 

 sequently what is necessary is not to alter the liquid but to make the 

 conditions of the exj)eriment as regards temperature as exact as pos- 

 sible. In this respect Huizinga's experiment is a confirmation of 

 Bastian's, and nothing more. 



He has recently repeated it with the same modifications as regards 

 temperature as those employed in his repetition of the turnij)-cheese 

 experiments. The results have been the same. In all other respects 

 he has followed the method described by him in his paper. 



He has prepared the solution of salts, grape sugar, and peptone in 

 exact accordance with his directions. To obviate his objection as to 

 the absence of air, he has introduced the liquid, not into flasks, but 

 into strong glass tubes closed hermetically at each end and only half- 

 filled with liquid, the remainder of the tube containing air at the 

 ordinary tension. Each of these tubes, after having been subjected to 

 the temperature of ebullition under two inches of mercury for half an 

 hour, has been kept since September 10 at the temperature of fermen- 



• See 'Xalure,' vol. viii., p. 141. 



