

VAN HELMONT'S THEOKY. 5 



that he had proved by a conclusive experiment that 

 all the products of vegetables were capable of being 

 generated from water. The details of this classical 

 experiment were as follows : 



" He took a given weight of dry soil 200 Ib. and 

 into this soil he planted a willow-tree that weighed 

 5 Ib., and he watered this carefully from time to time 

 with pure rain-water, taking care to prevent any dust 

 or dirt falling on to the earth in which the plant 

 grew. He allowed this to go on growing for five 

 years, and at the end of that period, thinking his 

 experiment had been conducted sufficiently long, he 

 pulled up his tree by the roots, shook all the earth 

 off, dried the earth again, weighed the earth and 

 weighed the plant. He found that the plant now 

 weighed 169 Ib. 3 ounces, whereas the weight of the 

 soil remained very nearly what it was about 200 Ib. 

 It had only lost 2 ounces in weight." l 



The conclusion, therefore, come to by Van Helmont 

 was that the source of plant-food was water. 2 



1 The History of the Chemical Elements. By Sir Henry E. Ros- 

 coe, F.K.S. (Wm. Collins, Sons, & Co.) 



2 Van Helmont's science was, however, of an extremely rudimentary 

 nature, as may be evidenced by the belief he entertained that the 

 smells which arise from the bottom of morasses produce frogs, slugs, 

 leeches, and other things ; as well as by the following recipe which 

 he gave for the production of a pot of mice: " Press a dirty shirt 

 into the orifice of a vessel containing a little corn, after about twenty- 

 one days the ferment proceeding from the dirty shirt, modified by the 

 odour of the corn, effects a transmutation of the wheat into mice." 

 The crowning point ill this recipe, however, lay in the fact that he 



