;i(i 



rent gel ol" such :i fibrillar}' consli'iirlion thai will he 

 difficult U) iiiiihilc in niiN' ollu-i' way. 



ll has oflni ix'c'ii essayed lo use cilhcr ifclaliii or aj*ai' 

 in lissuc cuHuih's and it has been fi('(|ii(nll\ staled in llie 

 lileralure thai Ihe tissue cells will grow in agar. Leo 

 L o e b '"- claimed that he observed, foi' instance, an in- 

 growth of different tissue cells in agar in \i\() and in vitro. 

 The L e w i s's, I n g e b r i g I s e n -'= ' and others observed 

 the same thing. 



In experiments made by myself* in trying lo cultivate, 

 fibroblasts in xitro in agai* and gelatin. 1 found that the 

 tissue celh are iniable to grow in agar or in agar mixed 

 with embryonic tissue juices or serum as I n g e b i* i g t s e n 

 269) observed it. The agar material is of (juile another struc- 

 ture than the fibrin coagulum. Agar is a dense, impenetrable 

 mass, not of the same spongy nature as the fibrin clot, but 

 of agar hydrate nature; the water is much more closely 

 bound and can not. for instance, be squeezed out as in 

 the case of the fibrin coagulunii. 1 have often seen the growth 

 of fibroblasts in agar and different mixtures of agar and 

 other substances, but by careful observation 1 alw ays found 

 the growth as a surface growth in between the solid agar 

 surface and the liquid, whatever it may be, serum or tissue 

 juice; or I could observe a growth apparently in the 

 agar, bid it was found to occur onh' when the agar mass 

 was broken into pieces and the cells were tiien found to 

 be located in between the solid agar and the fluid serum. In 

 I n g e b !• i g t s e n's -69) experiments agar was mixed with se- 

 rum at a temperature of 50 °C. for instance, and at that 

 temperature the fluid agar does not form a suitable mixture 

 with a liquid, the agar will then consist more or less of 

 lumps of agar and fluid apparentlj^ mixed. This experi- 

 ment and interpretation of this artificial growth of tissue 

 cells in agar suggested, that if we could make an artificial 



*) not publistied. 



