AUXETIC IN EXTRACTS 305 



unquestionably due to the putrefaction that this one 

 tube of extract induced divisions in the experimental 

 ten minutes. 



Now, this fact required very careful consideration. 

 A 100-per-cent solution of extract would not in itself 

 induce divisions in lymphocytes unless it was putrid. 

 When it is fresh this extract is not effective in the 

 experimental ten minutes. It appeared probable that 

 the extract does in itself contain some substance 

 which causes cell-division, but in the strength of the 

 extract of 100 per cent this substance is not present 

 in sufficient quantity for it to induce divisions in the 

 experimental ten minutes unless the whole extract is 

 putrid. The first thing to do was to concentrate 

 the extract and see if this theory was right. It was 

 appreciated that the concentration process at the 

 room temperature was a most unsatisfactory pro- 

 cedure, for if the extracts were tightly plugged 

 they did not evaporate down, but if they were left 

 open they became putrid. One of the jellies which 

 induced divisions by virtue of the putrid extract was 

 therefore boiled and tried again. Still it induced 

 divisions in lymphocytes. It was submitted to pro- 

 longed boiling, and yet it was effective. So it was 

 proved that the substance which it contained which 

 caused cell-division w r as thermostable. We can 

 boil these extracts with impunity, and their auxetic 

 action is not impaired. Hence we made some fresh 

 extract of suprarenal gland and evaporated it down 

 to dryness by boiling. It is, when dry, a hygroscopic 

 brown mass which is readily soluble in water. One 



