24 PROGRESS OF MICROSCOPICAL SCIENCE. 



by the publication of the well-known work of Dr. Bastian (whom he 

 compliments as having awakened the exhausted interest of physiolo- 

 gists in the subject), his special object being to repeat the much- 

 discussed turnip-cheese experiment. 



Everyone knows what Dr. Bastian's observation is. It is simply 

 this, viz. that if a glass flask is charged with a slightly alkaline 

 infusion of turnip of sp. g. 1015, to which a trace of cheese has been 

 added, and is then subjected to ebullition for ten minutes and closed 

 hermetically while boiling, and finally kept at fermentation tempera- 

 ture. Bacteria develop in it in the course of a few days. This experi- 

 ment has been repeated by Huizinga with great care, and the accuracy 

 of Dr. Bastian's statement of fact confirmed by him in every parti- 

 cular : yet, notwithstanding this, he thinks the evidence aiforded by 

 these results in support of the doctrine so inadequate, that he, 

 desiring such evidence, has thought it necessary to repeat the experi- 

 ment under what he regards as conditions of greater exactitude. 



Huizinga's objections to Bastian's experiment are two. First, 

 that when a flask is boiled and closed hermetically in ebullition, its 

 contents are almost entirely deprived of air, and (2) that cheese is a 

 substance of mixed and uncertain composition. To obviate the first 

 of these objections, he closes his flasks, after ten minutes' boiling, not 

 by hermetically sealing them, but by placing over the mouth of each, 

 while in ebullition, a porous porcelain plate which has just been 

 removed from the flame of a Bunsen's lamp. The hot porcelain plate 

 is made to adhere to the edge or lip of the flask by a layer of asphalte 

 with which the edge has been previously covered. The j)urpose of 

 this arrangement is to allow air to enter the flask, at the same time 

 that all germinal matter is excluded. It is not necessary to discuss 

 whether this is so or not. 



To obviate the second objection he alters the composition of 

 the liquid used : he substitutes for cheese, peptone, and for turnip 

 infusion, a solution containing in a litre of distilled water — 



The pho'sphate is prepared by precipitating a solution of calcium 

 chloride with ordinary sodium phosphate, taking care that the 

 chloride is in excess. The precipitate of neutral phosphate so 

 obtained is washed and then added to the saline solution in the 

 proiiortion given. On boiling it is converted into soluble acid phos- 

 phate, and insoluble basic salt, of which tlie latter is removed by 

 infiltration. Consequently the proportion of phosphate in solution is 

 less than that above indicated. 



To the filtrate, peptone is added in the proportion of 0*4: per 

 cent. 



The pejitone is obtained by digesting egg-albumen at the tempera- 

 ture of the body in artificial gastric juice made by adding the proi)er 



