EFFECT OF SALINE SUBSTANCES 523 



8°. Effect of saline top-dressings on the quality of the seed. — It may 

 be doubted, however, whether the relative proportions of starch are to be 

 considered as the cause of the relative vahies of different samples of seed 

 potatoes. This proportion may prove a valuable test of the probable 

 success of two samples when planted, without being itself the reason of 

 the greater or less amount of failures. With the increase of the starch 

 it is probable that both the albumen and the saline matter of the potatoe 

 will in some degree diminish, and both of these are necessary to its fruit 

 fulness when used for seed. 



The value of the saline matter is beautifully illustrated by the obser- 

 vation of Mr. Fleming, that the potatoes top-dressed with sulphate and 

 pitrate of soda in 1841, and used for seed in 1842, " presented a remark- 

 able contrast to the same vanety of potatoe, planted alongside of them, 

 but which had not been so top-dressed in the previous season. These 

 last came away weak, and of a yellowish colour, and under the same 

 treatment in every respect did not produce so good a crop by fifteen bolls 

 (3| tons) an acre." This observation, made in 1 842, is confirmed by the 

 appearance of the crops now growing (July, 1843) upon Mr. Fleming's 

 experimental fields. The prosecution of the enq-uiry opened up by his 

 experiments promises to lead to the most valuable practical results.* They 

 may teach us how to secure at all times a fruitful seed, and thus to dis- 

 pense with supplies of imported produce. 



§ 22. The composition of the turnip, the carrot, the beet, and the parsnip. 



1°. Composition. — The potatoe is characterised by containing a large 

 proportion of starch in connection with a small quantity of albumen — the 

 turnip and carrot by containing, in place of the starch, a variable pro- 



with the same manure. From these circumstances, I am of opinion, that if farmers were 

 careful in raising their own seed potatoes from land that has lain long in a state of rest (a) — or 

 where that cannot be had, the same object can be obtained by bringing new soil to the sur- 

 face by trenching as much as is necessary, or by the use of the subsoil-plough — failures of 

 the potatoe crop from the seed not being good, would become much less frequent. I am 

 somewhat confirmed in this opinion by the fact, that it has been found for the last dozen of 



J 'ears that generally the best seed potatoes have been got from farms in the moors or high 

 ands of the country. The reason of this may be that these high lands have been but of late 

 brought under crops of any kind, and many of them but newly brought from a state of nature, 

 and the superiority of seed potatoes from these high lands may not at all arise (as is gene- 

 rally supposed) from a change of soil or climate. 



" Potatoes raised on new soil, or on ground that has been long lying lea, are not so good 

 for the table as the others, being mostly very soft, and, by the following experiment, it would 

 appear that they contain a much less quantity of farina than those which are raised from 

 land that has been some time under crop, and, perhaps, this is the reason why they arc better 

 for seed. From one peck of potatoes, grown on land near Paisley, which has been almost 

 constantly under crop for the last 30 years, I obtained nearly 7 lbs. of flour or starch; and 

 from the other peck, grown on my bleach green, the quantity obtained was under 4 lbs., from 

 which it would seem that as the vegetative principle of the plant is strengthened, the farina- 

 ceous principle is weakened, and vice versa. Jas. Stirkat." 



Paisley, 22d November, 1842. 



(a) Mr. Finnie, of Swanstone, informs me that the growing of potatoes intended for seed upon 

 new land, has long been practised by good farmers. Mr. Little, of Carlesgill, near Langholm, 

 writes me that in Dumfriesshire, they obtain the best change of potatoe seed from mossy 

 land — of oats and barley from the warmer and drier climate of Roxburghshire. The grains, 

 he adds, degenerate by once sc/twJhg-, still looking plump when dry, but having a thicker husk, 

 and weighing two or three powids less per busiiei. The deterioration of seeds, in general, 

 is a cAemfco-physiological sut^ect of great interest and importance, and will doubtles.s soon 

 be taken up and investigated. 



* In the Appendix, p, 47, the experiments are recorded, and in p. 66 I have more fully ad- 

 verted to the interesting results likely to be derived from the continuance of auch experimenta. 



