3G6 MacDOUGAI^HYDRATION AND GROWTH. 



was greater than in those approaching maturity, representing the 

 extreme of this type. Four fruits less than a week old, with radial 

 diameters of 14, 16, 17 and 18 mm. were found to weigh 14.650 

 grams. These were fragmented and placed in a beaker on a water 

 bath at about 100° C. for 48 hours, at which time the dry material 

 remaining was 1.90 grams. From this it is to be seen that the young 

 fruit contained 87 per cent, of water and 13 per cent, of dry ma- 

 terial. A mature fruit of the same kind as those measured taken 

 September 10 from a ranch near the Coastal Laboratory was 46 

 mm. in axial diameter and 58 mm. in radial diameter and weighed 

 93.050 grams. This was dried over a water bath for 2 days, at 

 which time 8.400 grams remained. From this it is to be seen that 

 the ripe fruit contained 91 per cent, of water and 9 per cent, of dry 

 material. (See Anderson, S. P., "The Grand Period of Growth in 

 a Fruit of Cue iirb ita pepo DeterminQd by Weight,"' Minn. Bot. Stud., 

 i: 238, 1894-98; and MacDougal "Practical Text-book of Plant 

 Physiology, pp. 293, 294, 1918, New York.) 



A number of plants of the tomato were grown in suitable boxes 

 of soil at a ranch in the Carmel valley, and were in such a stage of 

 development that young fruits were available at the Coastal Lab- 

 oratory in August, 1918. 



Six plants in all were used and continuous records from fruits 

 of an axial diameter of 3 to 4 mm. to maturity at 50 to 55 mm. were 

 obtained. The fruits were oblate-spheroid in form and the auxo- 

 graph was arranged to register increase in diameter nearly parallel 

 to the axis in some cases and radially or at right angles to it in 

 others. In addition to the other advantageous features of this ma- 

 terial their regular form and mode of growth made it possible to use 

 the variations in diameter as a basis for calculating the changes in 

 volume of the fruits taken as spheres. 



Temperatures were taken by thrusting the thin bulbs of the small 

 thermometers into fruits near the one under measurement. The 

 development of such fruits was but little affected by this wounding 

 and the thermometer remained firmly in place as in the fleshy joints 

 of Opuntia, in the measurement of which this method was first 

 practised. The preparations stood in a well-ventilated glass house 

 and the soil around the roots was kept moist in accordance with the 



