598 APPENDIX C. 



the age of the Turnip. Judging from the period during which 

 my investigations were made, namely winter and early spring, I 

 suspect that they are developed only in preparation for sending 

 up the flower-stalk. 



Let me add that experiments on circulation in plants made 

 during the state of inactivity, when it is to be presumed that the 

 vessels and tissues contain but little sap, are much more suc- 

 cessful than those made in the summer. It would seem that 

 when the tissues are fully charged with sap the taking up of 

 dyes is comparatively slow and the above-described effects are 

 not so easily demonstrable. 



[An expert writes concerning this essay : — " I have not 

 attempted to annotate critically this paper. There is no doubt 

 that many of your conclusions are perfectly sound, particularly 

 those relating to the passage of crude sap through the cavities of 

 the elements of the wood, though the opinion that the actual 

 passage was through the walls very generally held till about 12 

 years ago."] 



