94 



1)V menus ol' :i loiij^ philiiiuin s|);itul:i Alter llie coajfulalion 

 has lakeii |)laee. llie lliiiil luediiiin is poui'ed on llie siirrace 

 ol" the elol and Ihc neck is rianied and closed by llic 



eolloii and a rui)l)er cai). 



The riiiid medium is changed every 2 lo 1 (hiys aeeoj-ding 

 lo the nature of tlie eultui-e. The fluid is as])iraled by 

 means of a pipette or an asj)Ji-aloi- and llie new fluid 

 introduced. It is claimed by Carrel'''^^ that it is possible 

 to handle about <i() flasks in one hour. 



The measurement of the rale of growth is luiderlaken 

 exacti} in the same manner as described foi- the hanging 

 drop cultures. 



By this method it has been observed that when the 

 area of growth of connective tissue or epithelium is plotted 

 in the ordinate and the time in abscissie the curve ex])ressing 

 the growlli is a parabola. This is only the case, when the 

 fluid medium contains nutrient substances. If the fluid me- 

 dium was composed only of Tyrode solution or serum, in 

 othei- words, a non-nutrient metlium. the growth represents 

 the residual activity of the tissue and the curve is generally 

 an S-shaped curve. 



The usual accidents by this method may be traced back 

 to bacterial contamination. Special care has to be taken, 

 when the same containers have lo be handled several times 

 during an experiment — but experience has taught that 

 bacterial contamination can be avoided when the ])ro|)er 

 care is taken. 



A culture of fibroblasts, epithelium or lymphocytes can 

 be kept in a condition of uninterrujjted life foi- about 3 

 weeks by this new method. 



Besides the methods for cidtivation of tissue cells in 

 vitro already described, there are still several methods of 

 explantations which are mere survivals of tissue cells in 

 vitro and cannot be called tissue cultivation and are used 

 by many investigators; it is not important and necessary 



