4 THE SCOPE OF THE NEW METHOD 



with dyes dissolved in alcohol have done something to 

 retard in-vitro methods of investigation, because dyes 

 dissolved in alcohol cannot, of course, be used to stain 

 living cells. As a matter of fact, with this new "jelly" 

 method it is simpler to stain certain living cells than it 

 is to stain dead ones by the old methods, and better 

 pictures are obtained although less skill is required. 

 No matter how rapidly a cell or tissue is killed, the 

 fact remains that it is dead, and the means usually 

 taken to prepare it for examination by placing it in 

 preservative solutions or in others necessary for fixing 

 and staining it not to speak of the processes of em- 

 bedding and freezing and the subsequent cutting with 

 razors and so forth can only add to the fallacious 

 results of its examination. So far as blood-cells are 

 concerned, the study of their morphology and cytology 

 has hitherto been almost entirely based on the exami- 

 nation of dead specimens, with the result that some 

 erroneous impressions, both as to form and func- 

 tion, have become generally accepted. For instance, 

 let an experienced worker with the older methods 

 look for a "hyaline leucocyte" with the new one, and 

 he will marvel at his credulity. The hyaline leuco- 

 cyte is a dead lymphocyte which has become achro- 

 matic. By the new method we see cells stained while 

 they are alive, and admirably spread out on the jellies, 

 so that they can readily be examined by the highest 

 powers. One can now cause any soluble substance to 

 diffuse into them at any rate one pleases, and with the 

 help of this knowledge one can, by specific chemical 

 agents, cause leucocytes and other cells to divide on 



