CONTENTS. 



Page. 



I. Introductory discussion 5 



II. Historical 24 



III. Experimental methods: 



Selection and preparation of material 26 



Preparation of material for estimation of sugars 26 



The determination of dry weight 27 



Preparation of material for analysis 27 



Calculation of analytical data 30 



The analysis of the sugar solutions 31 



The process of reduction 33 



The determination of copper 34 



The standardization of the solutions 35 



The estimation of the pentose sugars 36 



COj determination 38 



IV. The carbohydrates of the Cacti 39 



V. Seasonal variations in the carbohydrate-content 48 



VI. Effect of water on the carbohydrate-content 57 



VII. Effect of temperature on the carbohydrate-content 61 



VIII. Aerobic and anaerobic respiration 64 



IX. Consumption of carbohydrates during starvation 70 



X. Origin and role of pentose sugars 75 



