80 Mr. Knight on the direction of 



composition is very similar to that of the waters of Spa. Every 

 season the concourse of English visiters to those waters is con- 

 siderable : it may not, therefore, be uninteresting to medi- 

 cal men to learn, that these waters contain azote in consider- 

 able quantities: a fact not new in chemistry, but yet not 

 common, and of great importance. 



ON THE DIRECTION OF THE RADICLE AND GERMEN 

 DURING THE VEGETATION OF SEEDS. 



By THOMAS ANDREW KNIGHT, Esq., F.R.S., 

 President of the Horticultural Society, &c. 



TN the ' Quarterly Journal of Science ' of the last year, (of 

 which publication I regard the 'Journal of the Royal Insti- 

 tution' to be, in some degree, a continuation,) a communication, 

 made by M. Poiteau to the ' Societe d'Horticulture ' of Paris, 

 is noticed ; in which that writer considers himself to have 

 totally refuted and annihilated my hypothesis respecting the 

 descent of the radicle and ascent of the germ of germinating 

 seeds, which was published in the ' Philosophical Transactions ' 

 of 1806. M. Poiteau proceeds to slay the slain; for after 

 having, as he supposes, proved that my inferences are not 

 physiologically correct, he goes on to say that they are not 

 at all physiological, and that ' II convient done que les bota- 

 nistes raient 1'expe'rience de MM. Knight et Dutrochet du 

 catalogue des experiences de physiologic ve'getale,' having pre- 

 viously determined that ' il n'y a rien de physiologique dans 

 1'expe'rience de M. Knight.' 



I had previously seen several attempts to refute my hypo- 

 thesis 5 but, in all these, it was either misunderstood or widely 

 misrepresented. I must give M. Poiteau, however, the credit 

 of having fully understood and fairly represented my hypo- 

 thesis ; and the only grounds upon which I can object to his 

 conclusions are that, as far as they are connected with vege- 

 table physiology, all his premises and all his inferences are 

 false ; and that if all his premises had been perfectly true, all 

 his inferences would have been totally erroneous. 



M. Poiteau attached pieces of metal, of the form of the 



