161 



scattered The cover-glass was replaced on the slide, it was 

 scaled with paraffin, nnd an outline drawing was made of 

 the tissue of the l)ig i)iece as well of as tlie small one. 

 The culture was returned to the incubator for another 30 

 hours; at the end of the second incubation a new drawing 

 was made and the area measured. It was observed that the 

 mother culture had greatly increased in size, but the frag- 

 ment, separated from it by means of the wound in the clot, 

 consisted of scattered cells and had rathei" decreased in 

 size. (Fig. 32, 33.) It was observed that a peninsula had 

 grown on the surface of the cover-glass from the central part 

 of the main tissue, but that the separated small piece had 

 not increased in size, much less encroached on the open 

 space. 



The result of these experiments lead to the opinion that 

 it is not possible for one single isolated .cell, or for a few 

 isolated cells, to multiply in culture under the conditions of 

 experiment. The cells will live, but will not divide. We are 

 apparently not dealing with the growth of independent cells 

 in the tissue culture, but with a partial organism, a piece of 

 tissue, obeying the laws of regeneration. The cells seem to 

 be closely related, but their condition and capacity for 

 growth seem to depend on their neighbouring cells. 



In the discussion of these questions may there not be 

 other explanations why multiplication of isolated cells does 

 not take place in our experiments on the individualisation 

 of tissue cells? In other words is the method for the isolation 

 of living tissue cells, above indicated, so favourable that we 

 can assure ourselves that the cells are in good- condition 

 after transference? 



Some features which perhaps may play a more or less im- 

 portant part should now be mentioned. It has been shown 

 that in transferring tissues from one culture to another it is 

 important to put the tissues in the medium so that the cells 

 are in close contact with the medium. If we cut into a piece 

 of tissue in such a way that a bit of coagulated plasma from 



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