Imbibition and Growth in Fruits. 167 



8.400 grams remained. From this it is to be seen that the ripe fruit con- 

 tained 91 per cent of water and 9 per cent of dry material. In fact, 

 these fruits show a better parallel to the hydration reactions of the 

 prepared biocolloids than any living material which has hitherto been 

 examined for the purpose of estimating the value of the physical fac- 

 tors in growth. 



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 de- 

 velopment that young fruits were available at the Coastal Laboratory 

 early in August 1918. Six plants in all were used and continuous rec- 

 ords 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 

 auxograph was arranged to register increase in diameter nearly par- 

 allel 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 mate- 

 rial, the 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 small 

 thermometers into fruits near the one under measurement. The 

 development of such fruits was but little affected by this wounding 

 and the thermometers remained firmly in place, as in the fleshy joints 

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

 The preparations stood in a well-ventilated glass-house and the soil 

 around the roots was kept moist in accordance with the cultural re- 

 quirements of these plants. The results may be best set forth by the 

 description of the action of the several fruits measured. 



No. 1 was placed in the greenhouse and a fruit 29 nun. in diameter 

 was fixed on a block of hard cork in such position that it gave a radial 

 bearing to the auxograph, which was set to amplify changes in volume 

 by 5, on August 9. The record was kept continuously until September 

 18, at which time the radial diameter of the fruit was 51.5 nam. The 

 fruit was turning yellow on September 16 and was showing fluctuations 

 in volume comparable to those in No. 2, with which it was run in close 

 comparison and under almost exactly the same conditions of moisture 

 and temperature as recorded. 



No. 2 was adjusted to the auxograph in the greenhouse on August 9, 

 in such manner as to give modifications of the axial diameter, which 

 at this time was about 27 mm. The record was continuous until 

 September 18, at which time the diameter was 50.5 mm. This fruit, 

 like No. 1, was beginning to turn yellow on September 16. 



No. 3, 10 mm. in diameter, was adjusted to the auxograph to record 

 variations in radial diameter on August 21, and a record was kept 

 continuously with frequent notations of temperature and sunshine, 

 etc. It is to be noted that 1, 2, and 3 were under equable temperatures. 



