8: 



for every 1 cuttings or so to avoid bringing possible in lec- 

 tions material from one culture to another. 



The fragments of tissue arc ti'ansferred l)y means of the 

 knife }M)int to the me(nuni. They must be embedded llio- 

 roughly in it williout folding or curling. This step must be 

 cai'ried out ra])idly to guard against embedding after coa- 

 gulation has set in. In between the manijjulation the prepa- 

 rations are kept under a large Petri dish in order to 

 avoid bactericial contamination from the air. 



This techniciue briefly described here can l)e api)lied 

 to the cultivation of all kinds of tissues in general. Slight 

 modification may be necessary though in general the prin- 

 ciples are very much the same. It will be described in detail 

 in anothei- chapter. 



In the meantime, several investigators have tried to sim- 

 plify the culture-technique by operating with simpler and 

 less complicated media. As mentioned often before, Lewis 

 and Lewis ^^^) ^■'^) used different salt solutions with the 

 addition of chicken broth, agar, and so on; S w e z y ^9") 

 used a medium composed of egg albumin and muscle ex- 

 tract. The growth obtained in these various media was not 

 equal to that in plasma or hmiph. Ebeling and Carrel 

 found that the fibrin has no other value for the cells 

 thaji to serve as a scaffold for new cells. Ebeling ^•5-) 

 worked out a technique by which the medium was prepared 

 from fibrinogen, serum and tissue juice and quite recently 

 by using only fibrinogen, tissue juice and Tyrode's solu- 

 tion, or fibrinogen, egg albumin and tissue juice. In this way 

 it was possible to get rid of the growth inhibiting factor in 

 the serum. In the beginning there was some trouble in 

 using fibrinogen, tissue juice and egg albumin, for liquefac- 

 tion of the culture-medium occurred after a short period of 

 incubation. But this was overcome by adding a trace of 

 unsaturated fatty acids to the medium. Sodium linoleate 

 was used and no liquefaction occurred. The investigations 

 mentioned have just begun and can only be looked upon 

 as being of great value and importance. 



