360 Journal of Applied Microscopy. 



An Improvement in the Technique of Making Blood-Serum 



Culture Media. 



The usefulness of coagulated blood-serum, with or without the addition of 

 glucose bouillon (Loefifler's blood-serum mixture), as a general culture medium 

 for the propagation of pathogenic bacteria, makes its easy manufacture a great 

 desideratum. The original " slow " method, involving the use of special appara- 

 tus and a great expenditure of time, has now been abandoned in most laboratories 

 for the more satisfactory Councilman-Mallory method. While a great improve- 

 ment over the previously employed method, still most workers will agree that 

 even this procedure is open to certain objections, chief among which are the 

 necessity for more or less careful supervision of the process while the medium is 

 undergoing coagulation and the occasional complete destruction (or at least the 

 making of an unsightly product) by the bubbling which results from the acciden- 

 tal production of too high a temperature where the ordinary hot-air or steam 

 sterilizer is used in lieu of the special coagulating apparatus. 



For somewhat over a year I have employed a device which obviates these 

 and certain lesser difficulties, and makes the manufacture of slants of coagulated 

 blood-serum, or Loeffier's medium a procedure which is now undertaken with the 

 assurance of securing a perfectly satisfactory product at an expenditure of labor 

 not greater than is required for making a batch of nutrient agar and essentially 

 without the possibility of anything going wrong if the details are accurately 

 followed. This result is attained by the simplest possible device and with the 

 employment of only such apparatus as is found in even the most modest labora- 

 tory. In addition to obviating the difficulties above mentioned, this method 

 possesses marked advantages in the ease of sterilization of the medium and in 

 its keeping power. 



The blood is collected at the slaughterhouse in the usual manner, museum 

 jars of about four liters capacity, with clamped tops, being the best receptacles. 

 The jars are merely washed thoroughly and no attempt is made at rendering 

 them perfectly sterile. About half an hour after the blood is collected a clean 

 glass rod is passed around between the clot and the side of the jar, breaking up 

 any adhesions between the two. The jar is then left in a cool place for not 

 less than twenty-four hours, until the clot is quite firm, when the serum is 

 removed by means of a pipette with a bulb blown in it to increase its capacity 

 and with a soft rubber tube attached. During this step, and indeed up to the 

 point where the serum is poured into the test-tubes, no special aseptic precautions 

 are taken, mere cleanliness being all-sufficient. 



The serum is now run into test-tubes which have been previously sterilized 

 by dry heat, using for this purpose a filling funnel or, for small quantities, a 

 50 cc. burette. If an ordinary small funnel without special attachment is used, 

 the entrance of air bubbles is inevitable and these remain entangled in the 

 surface of the serum for some hours, giving rise to an unsightly product if the 

 serum is coagulated before they have completely disappeared. If Loeffier's 



