576 SCIENCE PROGRESS 



give the average rate for the whole of such a relatively long 

 period, and so may miss very large changes of rate which only 

 last for a short time. 



This series of studies has so far dealt mainly with the 

 effect of ether upon the respiration of bacteria, moulds and 

 seeds, and with the effect of salts [NaCl, KC1, and CaClJ in the 

 first two cases. The effect of ether is found to be the same 

 as has been previously recorded, except that by means of this 

 method of closer observation it appears that the changes are 

 quicker and larger than was to be expected. The effect of 

 ether is to produce an increase in the rate of respiration which 

 is not maintained but gives way later to a decrease. The 

 stronger the dose the quicker and more severe the result. 

 The maximum increases in rate recorded as the result of the 

 strongest dose used, i.e. a saturated solution of ether in water 

 (7-3 per cent.), are as follows : Aspergillus niger, 150 per cent, 

 normal in two minutes ; Bacillus subtilis, 5,000 per cent, 

 normal in one minute; wheat-seed, 150 per cent, normal in 

 fifteen minutes approximately. 



The effect of salts upon the respiration of Bacillus subtilis 

 is in the same sense as that of ether, namely, low concentrations 

 cause an increase and higher concentrations a decrease in the 

 rate of CO a evolution. The changes are, however, much milder, 

 and though they occur just as quickly, the changed rate is 

 maintained at a constant value. NaCl, CaCl 2 , and KC1, CaCl 2 

 are stated to antagonise each other in their effect upon 

 respiration. 



Perhaps the most notable contribution that has recently 

 been made towards our knowledge of the chemical complexity 

 of respiration is that contributed by H. A. Spoehr in one of 

 the publications of the Carnegie Institute of Washington, 191 9, 

 and entitled " The Carbohydrate Economy of Cacti." The most 

 interesting section of this paper is the introduction, which 

 brings under review in an able and illuminating manner for 

 the biologist converging lines of experimentation in chemistry, 

 physics, and physiology bearing upon the extraordinary com- 

 plex problems presented by the plant's carbohydrate meta- 

 bolism, in which respiration plays a fundamental part. In 

 the first place, in the light of modern developments, Spoehr 

 attempts to formulate the main features of the complex system 

 which constitutes the seat of metabolism in the living organism. 

 Protoplasm can no longer be regarded as a complex compound 

 of definite constitution entering into and supporting the processes 

 of metabolism. Rather it is to be considered as a physical 

 medium or substrate in the nature of a highly complex mixture 

 having two main characteristics : (1) colloidal nature ; (2) rela- 

 tive chemical stability. Upon this relatively permanent sub- 



