506 



BROOKLYN BOTANIC GARDEN MEMOIRS 



, Table i 



Net Absorption by Squash Seedlings from Solutions of Ca{N0i)2 



Original Concent, of 



Solution 



Ca(N03)2Xio-6 



Minimum Concent, of 



Solution as 



Ca(NO3)2Xi0-6 



Maximum Net Absorp- 

 tion Calc. as 

 Ca(N03)2Xio-« 



12. o grm. norm 50.0 grm. norm — 38.0 grm, norm. 



18.2 

 24-5 



36.4 

 38.0 



45-7 

 45-5 

 63.0 



96.3 

 182.6 



351-8 

 518.5 



693-5 

 867.0 



430 

 34-0 



32.1 



37.1 

 29.6 



36.3 

 34-6 

 34-0 

 29.6 

 39-1 

 47-8 



125-9 

 152.9 



- 24.8 



- 9-5 



+ 



4-3 



0.9 



16.1 



9.2 



28.4 



62.3 



153-0 



312.7 



470.7 



567.6 

 714.1 



concentration indicated in any case merely states the net result of 

 ion interchange in a given culture stated in terms of such a solution of 

 the given salt as would have a like electrical conductivity. 



As the quantity of salt is still further augmented, the unabsorbed 

 residue increases, indicating a clear surplus of this constituent. It is 

 interesting to note, however, that the unabsorbed residue does not 

 increase at a rate parallel with the quantity offered; the absorption 

 increasing also though at a lagging rate. The maximum quantity of 

 Ca(N03)2 absorbed by five plants out of a concentration of 867 grm. 

 norm. X io~® is about 714. i grm. norm. This expressed in weight of 

 salt absorbed per seedling would be about 0.0055 grm. This may be 

 taken to represent approximately the maximum quantity of Ca(N03)2 

 absorbed by a squash seedling living in darkness in a temperature of 

 18° C. during the time required by the seedling to exhaust its available 

 reserves. 



Calcium Sulphate 



A somewhat similar experiment was made in which calcium sulphate 

 was used, in the hope that we might get some light on the comparative 

 effect due to the sulphate and the nitrate anions. A series of 14 cul- 

 tures was set up using squash seedlings as before covering a range of 

 concentration between distilled water and 830 gram normals of the 

 salt in a million liters. The experiment ran from July 12 to 23, 1916. 

 A graphic record^ of the course of the concentration changes in the 

 several cultures is shown in the accompanying diagram (Fig. 2) : 



^ In order not to crowd the figure only one curve representing an original 

 CaS04 concentration less than 50 grm. norm, is given. 



