FURTHER RESULTS IN DESICCATION AND RESPIRA- 
TION OF ECHINOCACTUS 
EsMOND R. LONG 
(WITH ONE FIGURE) 
A description of the results of a series of desiccations of Echino- 
cactus carried out at this laboratory has been published, in which 
changes in the water and carbohydrate: balance with the accom- 
panying morphological variations were followed in some detail." 
The experiments were made under two sets of conditions, some of 
the plants being desiccated in diffuse light within the laboratory, 
while others were exposed in the open to the full force of the sun 
and wind. Besides the characteristic features of the water loss, 
such as its varying rate under different conditions, and the viability 
of the plants in the face of prolonged desiccation, a number of 
interesting discoveries were made as to the fate of the carbohydrate 
nutriment of the desiccated plants. It was found that Echinocacti 
drying in the open stored carbohydrate at a rate exceeding its loss, 
a large portion of the increase taking place in the “soluble non- 
reducing sugar’’ fraction (including cane sugar); and that in long 
desiccation in diffuse light oxidation of the stored sugars took place 
at such a rate that the dry weight of the plant tissue remained 
constant, as large a proportion of water being found after 6 years 
of desiccation in the case of one plant as was present in the begin- 
ning, in spite of a loss of nearly 30 per cent of its original weight by 
water depletion. These results were very striking, and it seemed 
that it would be of unusual interest to combine these effects in one 
plant, thereby obtaining new light on the course of katabolism 
in the various types of carbohydrate and on the time element 
involved. 
Accordingly, an Echinocactus which had been loaded with 
carbohydrate by desiccation in the open, after 8 months was placed 
in a ventilated dark chamber where photosynthesis was no longer 
* MacDoveat, D. T., Lone, E. R., and eae J. G., Physiological Researches, 
no. 6, August, 1915. : 
Botanical Gazette, vol.65)  . : Pi, [354 
