BY DR. 0. KATZ. 261 



In order to secure, in a suitable and unobjectionable manner, a 

 sufficient quantity of ice-water for analysis — the ice having, of 

 course, to be melted — I derived from the samples, by means of 

 a clean hammer, several medium-sized pieces, which, held by a 

 sterilised brass-tongue, were thoroughly washed by allowing 

 filtered rain-water carefully and for some time to flow over 

 them. (This rain-water had been boiling over the open flame for 

 about thi'ee hours). They were then placed and gathered in a 

 glass funnel (holding about 200 ccm.), which was covered by 

 another glass funnel of the same dimensions, and having a cotton- 

 wool stopper at its apex. After about ten minutes, during which 

 time a quantum of ice-water was allowed to waste, I put a small 

 Erlenmeyer's (or parting) flask (of 120-130 ccm. capacity) under, 

 the remaining portion of the mouth of which was covered with 

 sterile cotton-wool. In this way any possible contamination from 

 without was avoided. According to the temperature of the room 

 — the examinations took place in January and February, that is^ 

 in the middle of our semi-tropical summer —it lasted from three- 

 quai'ters to one hour, till 30-50 ccm. of melted ice had accumulated 

 in the glass-flask. I then removed it, replaced the stopper, 

 shook its contents gently and repeatedly, and immediately after- 

 wards proceeded to prepare cultures. The fact that the number 

 of bacteria in any sample of w&,ter increases considerably when 

 the latter is allowed to stand for some time, especially at 

 favourable temperatures, renders the immediate examination of 

 the water (or of the melted ice) a matter of necessity. For 

 instance, a sample of fresh ice-water yielded in 1 ccm. on the 

 average 407, in i- ccm. 194 bacterial colonies. After 54 hours, at 

 a temperature up to 28°C., the same sample contained in one drop 

 ( = 1-18 ccm.) innumerable numbers of colonies. 



The nutritive soil which served me for the cultivation of the 

 germs in the ice was a 10 i>.c. nutritive gelatine, of a slightly 

 alkaline reaction. To each sample of ice I took four gelatine- 

 tubes, of which two were inoculated each with Iccm., and the 

 two otheis each with ^ ccm. of the ice-water. The liquid gelatine 

 mixed homogeneously with such quantities of water, I solidified 

 after Esmarch's " roll-method," which is sufficiently known. The 



