EXAMINATION BY CULTURAL METHODS I47 



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 reaction 

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

 pain and annoyance." 



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

 for clinical work. The needle is carried ready sterilized, and no 

 time is wasted in boiling it, and the whole process may be per- 

 formed in five or ten minutes. The main disadvantage 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 Kiihnau 

 (ZeitscJwift f. Hyg. und Infct., 1890), 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 antiseptic precautions were used. 



The cultures thus obtained are incubated at the body tempera- 

 ture, 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 colonies appear on the agar tube, they are to be carefully 

 examined with a lens, and their characters noticed. The 

 organisms which will be most likely to develop are streptococci, 

 staphylococci, anthrax bacilli, pneumococci, typhoid bacilli, the 

 bacillus of plague, or the B. coli ; the gonococcus may also 

 develop, for it will obtain the haemoglobin necessary for its 

 development from the blood itself. 



