136 STEPHEN HALES 



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 dehghted with transforma- 

 tions." 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 1 726, before Vegetable Staticks. 



Nevertheless, Hales is not quite consistent about 

 the action of light ; thus (p. 351) he speaks of the 

 dull light in a closely planted wood as checking the 

 perspiration of the lower branches, so that "drawing 

 little nourishment, they perish." This is doubt- 

 less one effect of bad illumination under the above- 

 named conditions, but the check to photosynthesis 

 is a more serious result. In his final remarks on 

 vegetation (p. 375) Hales says in relation to green- 

 houses, "It is certainly of as great importance to the 

 life of the plants to discharge that infected rancid 

 air by the admission of fresh, as it is to defend them 

 from the extream cold of the outward air." This 

 idea of ventilating greenhouses he carried out in a 



