226 THE CYCLE CELL-DIVISION 



stained in an early stage of mitosis; its ring-shaped 

 nucleolus-centrosome was lying at a pole of the nucleus- 

 spindle in the cytoplasm, outside the mass of granules 

 which had not yet collected round the waist of the cell. 

 Now when this early figure was seen by me, I remem- 

 bered that I had seen something very similar to it before, 

 and on turning up a paper (British Medical Journal, 

 January 16, 1909), which described some work done 

 more than a year previously, it was found there men- 

 tioned that the nucleoli sometimes appeared outside 

 the nucleus in the cytoplasm. Now, this position of 

 the nucleolus-centrosome is the first step in mitosis, 

 and therefore it was grasped that this mitosis must have 

 been seen before, although the fact was not realised at 

 the time. Another far more important point was also 

 grasped, viz. that when the mitosis had been seen a year 

 previously, no extract of hsemal or any gland had been 

 either used or thought of. 



The notes of the previous work were referred to, 

 and it was found that when the as it turned out- 

 early stage of mitosis had been seen, the cells had been 

 resting on a jelly which contained only Unna's stain 

 and atropine. It was clear, therefore, that either one 

 or both these substances would induce divisions in 

 lymphocytes and our hopes were rather damped, for 

 both these substances, unlike the extract of haemal 

 gland, are entirely artificial, and could not possibly be 

 concerned in the cell-proliferation of healing. 



Each of the ingredients of the jelly described in 

 the last chapter which induced well-marked mitosis 

 in lymphocytes was now tried separately. Jellies were 



