LYMPHOCYTES MADE TO DIVIDE 183 



before we came to any conclusion as to the nature of 

 the bodies which had been observed in the cells. 



The first striking point noticed about the red- 

 staining rods was that they were not within the nuclei, 

 but were in the cytoplasm outside the nucleus. This 

 did not seem to be right, if tHte rods were chromosomes. 

 It is usually considered that the phenomena of mitosis 

 goes on within the nucleus as it does in plant-cells. 

 Hitherto, mitosis in human cells, or animal cells gener- 

 ally, had been seen only in cells which had been killed 

 and fixed with heat or chemical agents at a time when 

 they happened to be in the act of cell-division. From 

 observation by the older method, it was usually under- 

 stood that during mitosis the nuclear wall vanishes, 

 and the chromatin within the nucleus forms into 

 chromosomes, which then migrate into the cytoplasm. 

 We were prepared to believe that the older methods 

 might be fallacious owing to distortion caused by the 

 killing and fixing of the cells, and to the fact that 

 cells w^ere only caught in the act of mitosis, not 

 observed undergoing the whole phenomenon from start 

 to finish. If our observations were correct, the rods 

 in the lymphocytes were in the cytoplasm right enough, 

 but the nuclear wall was still there internal to the 

 chromosomes. 



The experimentation was then improved. Instead 

 of the dilute extract being used, a concentrated one 

 was made consisting of 50 grammes of ha3mal gland 

 chopped up in 50 cc. (i.e. 100 per cent) of citrate 

 solution, kept at 60 C. for twenty-four hours and then 

 filtered as before. A jelly-film was made thus: To a 



