68 STEPHEN HALES 



We have seen that as a chemist Hales is somewhat of a 

 solitary figure, standing between what may be called the periods 

 of Boyle and of Cavendish. This is even more striking in his 

 Botanical position, for here he stands in the solitude of all great 

 original inquirers. We must go back to Van Helmont, 1 577 1644, 

 to find anyone comparable to him as an experimentalist. His 

 successors have discovered much that was hidden from him, but 

 consciously or unconsciously they have all learned from him the 

 true method and spirit of physiological work. 



It maybe urged that in exalting Hales I am unfair to Malpighi. 

 It may be fairer to follow Sachs in linking these great men to- 

 gether and to insist on the wonderful fact that before Malpighi's 

 book in 1 671, vegetable physiology was still where Aristotle left 

 it, whereas 56 years later in 1727 we find in Hales' book an 

 experimental science in the modern sense. 



It should not be forgotten that students of animal physiology 

 agree with botanists as to Hales* greatness. A writer in the 

 EncyclopCBdia Britaimica speaks of him as " the true founder of 

 the modern experimental method in physiology." 



According to Sachs, Ray made some interesting observations 

 on the transmission of water, but on the whole what he says on 

 this subject is not important. There is no evidence that he 

 influenced Hales. 



Mariotte the physicist came to one physiological conclusion 

 of great weight^ ; namely, that the different qualities of plants, 

 e.g. taste, odour, etc., do not depend on the absorption from the 

 soil of difi'erently scented or flavoured principles, as the Aristo- 

 telians imagined, but on specific differences in the way in which 

 different plants deal with identical food material an idea which 

 is at the root of a sane physiological outlook. These views 

 were published in 1679 2, and may have been known to Hales. 

 He certainly was interested in such ideas, as is indicated by 

 his attempts to give flavour to fruit by supplying them with 

 medicated fluids. He probably did not expect success for he 

 remarks, p. 360: "The specifick diff"erences of vegetables, which 

 are all sustained and grow from the same nourishment, is 



^ Sachs, Geschichte, p. 502. Malpighi held similar views. 

 2 Ibid. , p. 499. 



