128 BACTERIOLOGY. 



small amounts of blood-serum from experimental ani- 

 mals which has been found very useful. The amount 

 of serum that can be obtained in this manner from a 

 small quantity of blood is much greater than in the 

 Nuttall bulb. The Latapie apparatus has been very 

 much improved and simplified by Rivas. 1 The advan- 

 tages of the Rivas modification are that it is much more 

 easily constructed and is far more durable that is, it is 

 less liable to break during sterilization and in subsequent 

 manipulations. 



The Rivas apparatus is constructed from two test- 

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

 one test-tube is drawn out into a long narrow neck 

 1 cm. in diameter and about 5 cm. in length. Three 

 or four points on the side of the tube are softened in 

 the flame of a blowpipe, and the softened glass driven 

 inward by means of a piece of pointed wood. This 

 gives supports on the interior of the tube to hold the 

 coagulated blood in place. Between the long narrow 

 neck and the body of the tube a constriction is formed 

 by drawing out the tube while heated. The second tube 

 also has a similar constriction about 20 cm. from its 

 mouth. 



The two tubes are now fitted together by inserting the 

 one with the long narrow neck into the second tube ; a 

 small amount of cotton being first carefully folded 

 around the neck of the first tube, so as to prevent the 

 entrance of dust. The two tubes are then fastened to- 

 gether by means of a wire twisted around the constric- 

 tion at the neck of each tube, and the apparatus is then 

 wrapped in cotton and sterilized in a hot-air sterilizer. 



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

 1901, p. 295. 



