ye STEPHEN HALES 



water. There are, however, pitfalls in this result of which Hales 

 was unaware, and perhaps the chief interest to us now is that he 

 considered the imbibition of the peas^ to be the same order of 

 phenomenon as the absorption of water by a cut branch 

 notwithstanding the fact that he knew^ the absorption to 

 depend largely on the leaves. It may be noticed that Sachs 

 with his imbibitional view of water-transport may be counted 

 a follower of Hales. 



In order to ascertain "whether there was any lateral com- 

 munication of the sap and sap vessels, as there is of blood in 

 animals," Hales (p. 121) made the experiment which has been 

 repeated in modern laboratories^ i.e. cutting a "gap to the pith" 

 and another opposite to it and a few inches above. This he did 

 on an oak branch six feet long whose basal end was placed in 

 water. The branch continued to " perspire " for two days, but gave 

 off only about half the amount of water transpired by a normal 

 branch^ He does not trouble himself about this difference, 

 being satisfied of " great quantities of liquor having passed 

 laterally by the gap." 



He is interested in the fact of lateral transmission in con- 

 nexion with the experiment of the suspended tree (Fig. 24, 

 p. 126), which is dependent on the neighbours to which it is 

 grafted for its water supply. This seems to be one of the 

 results that convinced him that there is a distribution of food 

 material which cannot be described as circulation of sap in the 

 sense that was then in vogue. 



Hales (p, 143) was one of the first ^ to make the well-known 

 experiment the removal of a ring of bark, with the result that 

 the edge of bark nearest the base of the branch swells and 

 thickens in a characteristic manner. He points out that if a 

 number of rings are made one above the other, the swelling 

 is seen at the lower edge of each isolated piece of bark, and 



1 The methcxi by which Hales proposed to record the depth of the sea is a variant 

 of this apparatus. 



2 Vegetable Staticks, p. 92. 



^ According to Sachs [Geschichle, p. 509) Ray employed this method. 

 -* Other facts show that the "gapped" branches did not behave quite normally. 

 ' He refers (p. J41) to what is in principle the same experiment (see Fig. 27) as due 

 to Mr Brotherton, and published in the Abridgment of the Phil. Trans, n. p. 708. 



