PREPARATION OF THE FILM 35 



together and the specimen is spoilt. In order to 

 overcome this difficulty, I asked Dr. Cropper to 

 make some experiments to try to ohtain fixed 

 films, which he has heen able to do by the following 

 process. We are now in possession of a few films 

 of lymphocytes from the peripheral circulation, 

 killed and fixed in the act of cell-division induced 

 by chemical agents (auxetics), and this has 

 enabled us to discard photography as our means 

 of recording the phenomena. 



(By J. W. CROPPER) 



By the following process one can fix and stain 

 any specimen of cells examined by the in-vitro 

 " jelly method." It is immaterial what chemicals 

 the jelly may contain ; and it does not matter 

 whether the chemicals are causing excitation of 

 amoeboid movements (kinetics) or are inducing 

 cell-division (auxetics), for description of which 

 former publications may be referred to. 



By way of example, in the present note I shall 

 describe the preparation and subsequent fixation 

 and staining of the film in which cell-division is 

 induced in lymphocytes. 



Preparation of the Jelly Film. As already 

 published, creatine, creatinine, guanidine, theo- 

 bromine, benzamidine, and other substances con- 

 taining the amidine grouping (N C = N) induce 

 mitotic figures in lymphocytes, and their action 

 is greatly increased by atropine, choline, and 

 cadaverine. We may use a mixture of theo- 

 bromine and atropine. 



TO a tube containing 5 c.c. of (S coefficient 



