70 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Experiment No. II. 



Virginian Stock, from Germination to the Flowering 

 Stage. 



One gramme weight of seed, containing 0*80 gr. of dry 

 Substance* and *14 gr. of water, was sown in each frame on 

 July 8, 1889, and the produce collected on September 1G, when 

 the plants grown in the frame without any covering glass were 

 in full blossom. Two plants only blossomed under the clear 

 glass, and none at all under any of the others, which remained 

 in a remarkably arrested condition. 



The following table gives the results obtained : — 







Totai weicrht 



Dry 



Gain or loss 



Dry sub. 



Water 





tenir.f 



( err*. ) 



sub. 



of dry snb. 



(p.c.) 



(D.C."> 



B 



64° 



20-80 



1-43 



+ '57 



G-87 



93-13 



Y 



71° 



30-65 



2-11 



+ 1-25 



6-88 



93-12 



G 



62° 



12-90 



•79 



- -07 



(M2 



93-88 



B 



(53° 



20-35 



2-05 



+ 1-19 



G-98 



93 02 



CI 



65° 



117-50 



1113 



+ 10-27 



9-43 



90-57 



Open .. 



(31° 



27900 



19-05 



+ 18-19 



G-82 



93-18 



From the columns of total weights and of the gains, it will 

 be seen that, for plants grown under coloured glasses, yellow 

 and blue are decidedly the best ; while green is conspicuously 

 the most injurious, an actual loss of dry substance having taken 

 place in the ten weeks during which the experiment lasted. 



The percentages of dry substance, however, reveal other 

 results. The proportion of water to dry substance is practically 

 the same under red, yellow, blue, and in the open ; while under 

 clear glass it falls considerably, presumably from the fact that 

 transpiration is more active, less water being retained in the 

 plants in consequence of the higher temperature. 



The great advantage accruing to the plants grown under no 

 glass at all is seen in the large amount of gain in dry substance, 

 viz. 18-10 grs., while under clear glass it falls to 10*27 grs. 



Here, then, as occurred with germinating Mustard, and as 

 will be seen with the Lettuces also, we discover two maxima of 

 assimilation as well as two minima. The former occurs under 

 yellow and blue, the latter under red and green. Hence these 

 experiments mutually corroborate each other in showing that 



• The seeds are too minute to enable one to separate the weight of dry 

 substance in the testa from that of the cotyledons. 



f These temperatures were taken on several occasions at mid-day in 

 September and in full sun, as well as at 9 a.m. 



