552 THE CULTIVATION OF TISSUE "IN VITRO." 



about 3 mm. long are dissected out with clean instruments, removed 

 to a coverslip, and covered by a drop of lymph freshly drawn from 

 one of the lymph sacs of an adult frog. The coverslip is inverted 

 over a hollow slide, and the rim sealed with paraffin wax. When 

 reasonable aseptic precautions are taken, tissues will live under these 

 conditions for from a week up to four weeks. 



GOLDSCHMIDT (Arch. /. Zellf., 1916) has investigated the sperm 

 cells of Lepidoptera by tissue culture methods. 



1038. Technique for Culture of Mammalian Tissues. Preparation 

 of the Animal for Procuring Plasma. The animal is anaesthetised 

 with ether, and must be kept just at the correct depth of anaesthesia. 

 A. J. WALTON (Journ. Path, and Bact., xviii, 1914), from whose 

 article the following paragraphs are partly culled, recommends for 

 this purpose a wide-necked bottle, with a closely-fitting cork pierced 

 with two tubes of wide bore, both of which pass down to within 

 |-inch of the surface of the ether placed in the bottle ; one tube 

 communicates with a tin funnel having a mackintosh flange ; this 

 tube also has a side tube, and the other tube is open to the air. 



The animal's head is placed in the funnel, and, when the side tube 

 is clamped, breathes air and ether vapour. By clamping either the 

 side or the short tube the amount of air or ether can be suitably 

 controlled. 



The hair of the throat, is either shaved off, or removed by the 

 application of a solution of sodium sulphide ii ad Oi, which rapidly 

 dissolves it. The skin is then sterilised by painting with a 2 per cent, 

 solution of iodine in spirit. 



1039. Preparation of Instruments, etc. Previous to the operation 

 the following apparatus is sterilised : Short test tubes, 2J inches 

 in length ; corks kept in stoppered bottles, to fit these tubes ; small 

 glass cannulse in olive oil ; three glass tubes, 3 inches by 1 inch ; 

 several narrow-bore pipettes which are kept corked in the last- 

 mentioned tubes, and which just before the operation on the animal, 

 are removed from the tube by means of sterile forceps, dipped in a 

 deep tin of molten paraffin, everted to allow the paraffin to run out, 

 and when cool placed in another sterile tube. 



Two small sterile test tubes, as mentioned above, are similarly 

 treated in paraffin, and should be corked with sterile corks as soon 

 as cool. These two tubes are placed in two other larger tubes made 

 to fit the centrifuge, and ice is packed between. 



Just before the operation, the instruments and some rubber teats 

 to fit the pipettes are boiled in water for ten minutes. 



