BLOOD-SERUM. 113 







burning off in the gas flame the excess of cotton pro- 

 truding from the ends of the tubes and then forcing 

 down upon the cotton plugs clean, new, corks that have 

 been sterilized by steam under pressure. (Ghriskey.) 



To secure satisfactory results by this method several 

 precautions should be noted, viz. : The solidification of 

 the serum in the dry air sterilizers must be complete, else 

 its surface will be rough and broken by bubbles ; the 

 same results if the temperature in the dry air sterilizer 

 is brought up too rapidly. 



Serum prepared in this way is neither clear nor color- 

 less. This is ordinarily not a disadvantage. The pop- 

 ularity of the method is due to its simplicity, the 

 rapidity with which a satisfactory serum may be pre- 

 pared and especially to the fact that the rigid precautions 

 against contamination observed in the older methods, 

 where sterilization at low temperature was practised, 

 are not essential to success, since even though such con- 

 taminations occur they are eliminated by the high tem- 

 peratures used in this proceedure. 



BLOOD SEBUM FROM SMALL ANIMALS. For special 

 purposes it is often desirable to secure blood serum 

 under strictly aseptic precautions from particular species 

 of animals, many of them being small. To this end 

 there have been devised a number of handy methods. 

 That which in our hands has proven the simplest and 

 generally most useful is the Rivas modification 1 of Lata- 

 pie's method. It is as follows : 



The Rivas apparatus is constructed from two test- 

 tubes about 15 x 180 mm. in size. The mouth of 



1 Rivas : University of Pennsylvania Medical Bulletin, vol. xvii, 

 1904, p. 295. 

 8 



