198 CLINICAL BACTERIOLOGY AND H^MATOLOGY 



with moderate pressure, in order to produce distension of ves- 

 sels. The needle is then plunged into the vessel, and generally 

 blood begins to flow by the blood-pressure itself, but any quan- 

 tity desired may be obtained by making gentle suction, either 

 by applying the mouth directly to the end of the tube where it 

 is stopped with cotton, or through the medium of a small piece 

 of rubber tubing slipped over it. 



"By the above instrument vein punctures have been made 

 in about 150 cases of a variety of diseases. At no time was 

 any difficulty experienced in obtaining the amount of blood 

 desired, which was generally about i c.c. In a few instances 

 it was necessary to try two punctures before securing a free 

 flow through the needle; in no case was there any local re- 

 action whatever at the seat of puncture, nor did the patient 

 complain of pain and annoyance." 



I used this method for years, and found it by far the best for 

 clinical work. The needle I employ is made for me by Down, 

 and differs somewhat from that illustrated in being expanded 

 in the middle, so as to hold rather more than 10 c.c., and is 

 graduated in cubic centimetres. It is kept in a wide test-tube 

 plugged with cotton-wool, the whole being sterilized by dry 

 air, so that no time is wasted in boiling it, and the whole pro- 

 cess may be performed in five or ten minutes. The main 1 dis- 

 advantage is that it requires a special instrument, whereas an 

 all-glass exploring syringe should be always available. 



The advisability of employing some such method in which 

 the blood is drawn directly from a vein .in place of the simple 

 skin puncture is very apparent from the researches of Kuhnau, 

 who made parallel series of experiments by the two methods. 

 He found that in cases in which the blood drawn directly from 

 the vein remained sterile, growth (mostly streptococci or 

 staphylococci) occurred in as' many as 90 per cent, of cultures 

 inoculated from skin punctures, though the most careful anti- 

 septic precautions were used. 



The cultures thus obtained are incubated at the body tem- 

 perature, and examined from day to day. The blood in the 

 broth tube 'will coagulate, and the appearance of growth may 

 be delayed by the entanglement of the colonies in the clot; 

 sooner or later, however, the clear fluid will become turbid if 

 bacteria are present, and subcultures can be made on agar or 

 blood-serum, and films examined. If a virulent streptococcus 



