MICROCOCCUS GONOERHCEM 293 



The appearances coincide with the figure of such a 

 colony given by Wertheim. 1 



Wassermann 2 calls attention to the success he has 

 had in cultivating this organism upon a mixture of 

 swine-serum and nitrose, the latter being a com- 

 mercial product chemically known as casein-sodium 

 phosphate. 



The preparation of the medium and its composition 

 are as follows : 



In an Erlenmeyer flask mix 15 c.c. of swine-serum, as 

 free as possible from haemoglobin ; 30 to 35 c.c. of water ; 

 2 to 3 c.c. of glycerin ; and finally 0.8 to 0.9 gramme 

 (i. e., about 2 per cent.) of nitrose. This is boiled, with 

 gentle agitation, over a free flame, until all ingredients 

 are dissolved and the cloudy fluid has become quite 

 clear. After such boiling the mixture can be sterilized 

 by steam without precipitating the albumin, and may 

 then be kept indefinitely ready for use. 



When needed, the flask and its contents are heated to 

 50 C. ; from six to eight tubes of 2 per cent, peptone- 

 agar-agar are dissolved by boiling, brought to 50 C., 

 and then mixed with the solution in the flask and the 

 mass poured into Petri dishes. Upon the surface of this 

 serum-nitrose-agar the cultivation is to be conducted. 

 Wassermann lays particular stress upon two points that 

 are essential to success, viz., the preliminary boiling of 

 the serum-nitrose mixture before steam sterilization, as 

 this prevents precipitation of the albumin ; and the 

 necessity of having both the serum-nitrose mixture and 

 the agar-agar, to be mixed with it, at not over 50 C., 



1 Deutsche med. Wochenschrift, 1891, No. 50 ; Centralblatt fur Gyna- 

 kologie, 1891, No. 24. 



2 Zeitschrift fur Hygiene und Infektionskrankheiten, Bd. xvii. p. 298. 



