.S8 



The |)i('|);ti-;ili<»ii i>t' tin- lilJiMnogcn is carried out :ul mo- 

 dum Milhinb.N '" or hy precipitation with piirilicd CO,,. 

 The t'ibrino^t'ii suspended in a small amount of distilled 

 watei- had the a|)j)earance of rich milk This suspension 

 could easily he redissolvcd in serum or Tyrodes solution 

 and hy tin addition of enil)ryonic tissue juice to the fihri- 

 nof^en serum or rihi*ino<feii-'ryrode solution jfave a clear lii'ni 

 clot. The j.;ro\\lh in a medium composed of 12..") ".i lihrinoi^en 

 suspension. .'{7.5 "o serum and .50 o/o eiuhryonic tissue juice 

 was a little less extensive than in the medium coni]K)sed 

 of plasma and tissue juice. Tlir advantages of using fibri- 

 nogen are numerous and will he still more valuable when 

 the scrum itself can h(^ (eliminated. 



rm-: rate of growth and its estimation.) 



It has often l)een observed (hat two fragments of the 

 same tissue placed in identical media do not grow at the 

 same rate and that these differences in rate of gi'owth can 

 be explained as technical errors. It is therefore highly im- 

 portant to know a little about these technical errors in 

 order to be able to judge an experimental result. E b e- 

 1 i n g "'•■'^ has investigated this particular point and found 

 thai the experimental erroi- in regard lo such complicated 

 experiments could be reduced to less than 10 "o. Special 

 care has to be taken in the selection of the cultures for 

 experiment, preparation of the tissue and the preparation 

 of the nu'dia according to labeling. 



SELECT10X70F THE TISSUE. 



The cultures lo be selected for exj^ei'imcnts have lo be in a 

 healthy condition, i. e., the central portion must not be 

 too thick and dense; there will often be a necrotic part. 

 The necrotic portions can easily he detected by their com- 

 plete opacity to Iransmiltcd light and they apiiear as white 

 spots when seen by reflected light. The tissue for ex- 

 periments is best when it has an even, good density of 



