EXPERIMENTS UPON THE LIVING ANIMAL.' 139 



which have been liquefied, and allowed to cool almost to the point 

 of gelatinisation, must then be poured over it. From a potato a 

 little cube mtist be cut, the tissue deposited in the trough thus 

 formed, and the cube replaced, or cultures may be prepared by any 

 of the methods which have been described for dealing with anaerobic 

 bacteria. Blood may also be taken directly from a vein by laying it 

 bare by dissectipn, making a small opening with sterilised scissors, 

 and inserting a looped platinum needle, the needle of a hypodermic 

 syringe, a capillary tube, or the extremity of the capillary neck of 

 a Sternberg's bulb. If the cultivation, in spite of these precautions, 

 is contaminated, or if there was more than one organism present 

 in the blood or tissues under examination, it will be necessary to 

 separate the different kinds by plate^cultivation. 



Having completed the dissection, the organs of such a small 

 animal as a mouse may be removed en masse, and transferred to 

 absolute alcohol for subsequent examination. In other cases it may 

 be only necessary to reserve portions of each organ. In experimenting 

 with a vii'ulent micro-organism hke anthrax, any remaining part of 

 the animal should be cremated, and the hands and all instruments 

 should be thoroughly disinfected. 



Isolation of Micro-organisms during Life. — Micro-oi'ganisms in 

 the living subject may be isolated from the pus of abscesses, or 

 ■other discharges, and from the blood and tissues. Abscesses should 

 be opened, and other operations performed, when practicable, with 

 Listerian precautions, and a drop of the discharge taken up with 

 a looped needle or capillary pipette, as already explained. 



To make a cultivation from the blood of a living person, the tip 

 of a finger must be well washed with soap and water and sponged 

 with 1 in 20 carbolic. "Venous congestion is produced by applying 

 an elastic band or ligature to the finger, which is pricked with a 

 sterilised sewing needle. From the drop of blood which exudes the 

 necessary inoculations and examinations can be made. Another 

 way of extracting blood from the living patient is to apply a leech. 

 This method has been found of considerable value in experimenting 

 upon the blood of patients suffering from malaria, and may be 

 useful in other diseases, if the blood is required for further 

 examination, or in quantity. 



