56 



Physico-Chemical Properties of Vegetahle Saps [March, 



were intentionally taken. The fruits were scrutinized again with 

 regard to this character and to maturity of seeds as they were dis- 

 sected. In general, only fruits whose seeds were on the average 

 more than half covered by the aril were used. All the fruits which 

 showed any indication of the whitening of the wall which precedes 

 the development of the red color, assumed in ripening, were dis- 

 carded, as were also those in which the arils had assumed very 

 much color. 



Before leaving the question of materials, it may not be out of 

 place to indicate the relative weights of the fruit wall (freed from 

 seeds) and of the abnormal carpellary mass. The averages for the 

 individuals samples are given in Tables 2-6. 



The average of the mean weights for the three series of obser- 

 vations which are large enough to make it worth while to compute 

 the probable errors are : 



Thus, the mean weight of the included mass is only two thirds of 

 that of the fruit wall. In only a single sample does the weight 

 of the prolification exceed that of the ovary wall. 



3. Experimental methods. A. Collection of Material. 

 In any study of cell sap it is essential that the Juices be obtained in 

 a condition as nearly as possible identical with that in which they 

 occur in the vacuoles of the protoplasm. In gathering the fruits, 

 every reasonable precaution consistent with the magnitude of the 

 task which had to be accomplished was taken to (a) secure fruits 

 in a condition free from external moisture or contamination ; {h) 

 to protect them from loss of moisture by evaporation; (c) to pre- 

 serve the wall of the ovary and the included mass, after dissection, 

 in such a way as to incur as little change as possible in the condi- 

 tions of the tissues; and, {d) above all, to avoid bringing about 

 any artificial differences between the compared samples. 



To attain these ends the fruits were collected with great care 

 and dissected as soon and as rapidly as possible. The proliferous 



