8o STEPHEN HALES 



the track and had he known as much as Priestley it would not 

 have been phlogiston that kept him from becoming a Cavendish 

 or Lavoisier. What chiefly concerns us however is the bearing 

 of Hales' chemical work on his theories of nutrition. He con- 

 cludes that "air makes a very considerable part of the substance 

 of Vegetables," and goes on to say (p. 211) that " many of these 

 particles of air " are " in a fixt state strongly adhering to and 

 wrought into the substance of" plants^ He has some idea 

 of the instability of complex substances and of the importance 

 of the fact, for he says^ that " if all the parts of matter were only 

 endued with a strongly attracting power, [the] whole [of] nature 

 would then become one unactive cohering lump." This may 

 remind us of Herbert Spencer's words: "Thus the essential 

 characteristic of living organic matter, is that it unites this large 

 quantity of contained motion with a degree of cohesion that 

 permits temporary fixity of arrangement," First Principles, 103. 

 With regard to the way in which plants absorb and fix the " air " 

 which he finds in their tissues, Hales is not clear ; he does not 

 in any way distinguish between respiration and assimilation. 

 But as I have already said he definitely asserts that plants draw 

 " sublimed and exalted food " from the air. ,' / ,' 



As regards the action of light on plants, he suggests (p. 327) 

 that " by freely entering the expanded surfaces of leaves and 

 flowers " light may " contribute much to the ennobling principles 

 of vegetation." He goes on to quote Newton {Opticks, query 30): 

 "The change of bodies into light, and of light into bodies is very 

 conformable to the course of nature, which seems delighted with 

 transformations." It is a problem for the antiquary to determine 

 whether or no Swift took from Newton the idea of bottling and 

 recapturing sunshine as practised by the philosopher of Lagado. 

 He could hardly have got it from Hales since Gulliver s Travels 

 was published in 1726, a year before Vegetable Staticks. Timiria- 

 zefl", in his Croonian Lecture^, was the first to see the connexion 

 between photosynthesis and the Lagado research. 



^ He speaks here merely of the apples used in a certain experiment, but it is clear 

 that he applies the conclusion to other plants. 



2 Vegetable Staticks, p. 313. It should be noted that Hales speaks of organic as 

 well as inorganic substances. 



* Proc. R. Soc. Lxxn., p. 30, 1903. 



