544 



Agricultural Chemistry — Turnips. 



Description of Turnips. 



Percentngo 

 of Dry 

 Matter in 

 Turnip 

 Bulbs. 



Norfolk White (lowest of experimental series) . . 



„ (highest of experimental series) . , 

 , „ (mean of experimental series) . 

 „ „ by farm-yard dung in experimental series 

 Green common turnip, by farm-yard dung .... 

 ,, by superphosphate of lime . 



Swede, Skirving's green top 



„ purple top 



„ purple top (old variety, name unknown) . 



whites to 12-25 in the purple- topped swede, or more than 5 J per 

 cent. ; but there is little doubt that it is dependent on the variety 

 of plant, rather than upon any effects of manure or culture. 



As a general inference from our results, we may state that the 

 mineral and carbonaceous manures, which we have before seen to 

 favour bulb-formation, — that is^ to determine to an early maturity^ 

 are those which in a given time will yield the largest percentage 

 of dry matter in the bulb ; but nitrogenous manures, on the other 

 hand, which v/hen in excess do not enhance bulb-formation (a 

 process of deposition), but rather an extension of the leaf or more 

 vascular system of the plant, involving a prolonged tendency to 

 active circulation^ and consequently a higher amount of vehicular 

 watery fluid in proportion to fixed substance, will afford a smaller 

 percentage of dry matter in the produced bulb. 



Were we, assuming bulb-formation to succeed leaf-formation, 

 to judge from some analogy furnished by other plants, we might 

 expect that the earlier organ, the leaf, would contain a less per 

 centage of dry matter than the later one, the bulb ; but inasmuch 

 as the dry matter is frequently about twice as great in the former 

 as in the latter, any such reasoning would imply a wrong con- 

 ception of the physiological relationship of the two organs. 



VYe regret that the entire series of leaves of this 3rd year of 

 our experiments was not collected for drying, and that indeed 

 none were taken until after the first weighing of the crops, a few 

 weeks later than the specimen-bulbs were gathered. We shall 

 not, therefore, employ the results for any more important purpose 

 than to show how far the effects of manures are the same in kind 

 as in the case of the bulbs, determining to the depositing or to the 

 more circulatory tendencies of growth. 



Here again we find no considerable variation, yet sufficient in 

 amount and in uniformity to render the mean results reliable for 

 our present purpose. The plants by mineral manures alone^ in 

 the first column, which were the furthest advanced in maturation 



