368 MacDOUGAL— HYDRATION AND GROWTH. 



Average daily rate of growth measured as increase in diameter 

 was as follows for periods beginning as follows : 



Aug. gth. Aug. i6th. Aug. 21st. Aug. 28th. Sept. 4th. Sept. nth. 



1.7 mm. I.I mm. 0.7 mm. 0.4 mm. 0.28 mm. 0.17 mm. 



Average daily rate of increase in volume : 

 1.953 cu. mm. 1,885 cu. mm. 1,548 cu. mm. 1,036 cu. mm. 732 cu. mm. 521 cu. mm. 



The rate on September 11 by direct measurement would ap- 

 pear to be one tenth that of a month earlier, yet actually water and 

 new material was being added at a rate equivalent to one fourth of 

 the earlier rate. The radial proportions would make the rate on 

 August 21 not much more than 40 per cent, of the rate on August 9, 

 while the increase in volume was over 96 per cent. The rate in the 

 week beginning August 28 would appear to be less than a fourth 

 that by direct measurement on August 9. yet actually the increment 

 of water and material is more .than half that in the younger stage 

 and smaller size. 



A second plant with the auxograph bearing arranged to take 

 axial variations in the fruits which measured 33 mm. was arranged 

 to run concurrently with No. i and under identical temperature and 

 conditions of moisture. The daily rates of increase in diameter 

 were as follows for the periods beginning : 



Aug. 9th. Aug. i6ih. Au_g-. 2ist. Aug. 2Sth. Sept. 4th. Sept. nth. 



0.95 mm. 0.7 mm. 0.56 mm. 0.3 mm. 0.2 mm. 0.2 mm. 



Daily rates in terms of volume : 

 1,563 cu. mm. 1,388 cu. mm. 1,274 cu. mm. 949 cu. mm. 380 cu. mm. 420 cu. mm. 



Here again the actual course of growth as calculated in terms of 

 volume shows that simple measurements of the thickness do not 

 express the real values in growth in such organs. 



The third test was made on a fruit taken at a much earlier stage 

 at a diameter of 16 mm. with a transverse or radial bearing, the tem- 

 perature and moisture conditions being similar to those of i and 2. 

 The daily rate of increase was as follows for the weeks beginning 

 on the following dates : 



Aug, 2ist. Aug. 28th. Sept. 4th. Sept. II. Sept. i8th. Sept. 2sth. 



.85 mm. .85 mm. .64 mm. 8. mm. .3 mm. .^l mm. 



Daily rate in volume : 



537CU. mm. 851 cu. mm. 885 cu. mm. 1,6431 cu. mm. 594cu. mm. 662 cu. mm. 



