THE SOURCES OF THE NITROGEN OF VEGETATION, ETC. 549 



equal to about 2^ times the volume of the shade. Carbonic acid also daily supplied, in 

 amount as described at pp. 480, 481. 



June 6. — Graminaceous plants (Nos. 1, 2, 3, 6, 7, 8, & 9) all healthy, though with a 

 tendency to turn yellow at the tips of the leaves. Of the Leguminous plants, Nos. 5, 

 10, and 11 give indications of dying. 



June 8. — Some of the wheat and barley plants turning yellow. Beans Nos. 5, 10, 

 and 11 obviously dying; probably injured by the causticity of the ash added to the soil, 

 as No. 4 beans, the^ seeds and roots of which happen to be washed when water is sup- 

 plied, are healthy and vigorous. 



Records fob each Experiment given separately. 



No. 1. — Wlieat (1857); six seeds; prepared soil ; without nitrogenous manure. 



(See Plate XV. fig. 1.) 



June 9. — Five plants up ; one quite small, the others 2 to 4 inches high, with two 

 leaves developed and a third appearing ; yellowish at the tips of some of the leaves. 



June 15. — Five healthy plants, each with three fully developed leaves; tips of the 

 lower leaves slightly yellow. 



June 24. — Plants 5 inches high ; lower leaves dead and dry, upper pale green ; with 

 some of the tips yellow, but general appearance of the upper leaves healthy. 



July 4. — Plants 6 to 7 inches high ; 5 leaves on each ; upper ones pale green, lower 

 ones yellow. 



[Note. — Drops of water condense rapidly on the tips of the leaves of all the Cereals, 

 but not of the Leguminous plants ; they also form and run down the inner surface of all 

 the shades, casting focal rays apparently injurious to the plants when not shaded from 

 direct sunlight.] 



July 11. — Same number of leaves ; very little further growth ; lower leaves more 

 dried up. 



July 22. — Very little improvement. 



July 29. — Very little growth, though upper leaves continue green; but little ten- 

 dency to form stem. 



[Note. — Shade opened a few seconds to substitute a tube for one accidentally broken.] 



August 10. — Green colour maintained, but no apparent increase in size. 



August 24. — Five plants, 6 to 9 inches high, with eight or nine leaves each, all dried 

 up but the two upper ones, which are green and healthy, one expanded, the other folded 

 in the axis of growth. The healthy appearance of the upper leaves has been maintained 

 several weeks, with otherwise almost total cessation of growth. 



October 3. — Plants taken up : — 



The plants have been almost stationary since the last report; termination of the 

 ascending axis keeps green ; no indication of heading. (See Plate XV. fig. 1.) 



Soil moist, soft, and spongy. 



Roots not distributed generally throughout the soil ; a few isolated ramifications 



