88 Upon the Cultivation of the Persian Varieties of the Melon, 



it is through the cellular substance, and not through the tubes of 

 the alburnum, that the sap ascends, or its ascent would be pre- 

 vented, which it is not, by intersection of those tubes, and those 

 tubes are also dry at Midsummer, when the sap is rising to supply 

 moisture to the leaves in great abundance ; previously to the dis- 

 coveries of M. Dutrochet, I had shown that the sap of trees is 

 lightest, or least dense, near the ground ; and that in any particular 

 tree, the weight of the sap increases as its distance from the ground 

 through the course of the alburnum increases : and I had also 

 proved that saccharine matter exists in considerable quantity in the 

 sap in the spring, in cases where no vestige of it can be discovered 

 in winter : and sugar was the material employed by M. Dutrochet 

 to form his denser fluid. These facts were not in any degree 

 known to M. Dutrochet, when he made his discoveries, and he 

 therefore was certainly not led in any degree by me in making 

 them. 



The sap in the leaves of my Melon plants, was certainly a denser 

 fluid than the water with which they were sprinkled, and there- 

 fore, I imagine, that the latter fluid, passed in injurious excess into 

 the cells and vessels, and that the ingress and circulation of the 

 proper fluid, which ought to have continued to ascend from roots 

 was to a great extent prevented ; and that the creation of the true, 

 or living sap of the plant almost wholly ceased. The plant con- 

 sequently, I conclude, ceased to grow, and the fruit fell off, owing 

 to want of proper nutriment ; soon after I had ceased to sprinkle 

 the under surfaces of the leaves, the young fruit began to set well, 

 and the plants to grow ; but never with very great vigour ; and 

 the fruit, though its quality was exceedingly good, was smaller a 

 good deal than I conceived it would have been, if the under sides 

 of the leaves had not been so frequently wetted. The weather 

 was, however, very unfavourable, and the fruit, I entertain no doubt, 

 would have been larger, if the foliage of these plants had received 



