176 STUDIES ON RESPIRATION. I 



figures expressing time are omitted from the abscissae in order to avoid 

 confusion. 



In averaging curves the following procedure was adopted. A 

 curve was drawn for each experiment (plotting rate of respiration as 

 ordinates and time as abscissse). These curves were averaged 

 graphically, making use of interpolated points. It may be stated 

 that this procedure is perfectly sound since the error of interpolation 

 is usually less than the experimental error. 



The rate of respiration is stated in all cases as per cent of the 

 normal rate (which is always taken as 100 per cent). The rate is 

 taken as the reciprocal of the time required to produce the standard 

 change in acidity. The time required to produce this change under 

 normal circumstances is usually stated, and from this the actual 

 time required to produce the same change under the influence of 

 the reagent may be easily calculated. It is not necessary to find 

 the reciprocals of the time under normal and abnormal conditions 

 and then to divide the latter by the former in order to get the rela- 

 tive rate; for the same thing is accomplished more quickly by divid- 

 ing the time required to produce the standard change under normal 

 circumstances by the time required to produce the same change 

 under the influence of the reagent. 



Of particular interest is the fact that these investigations were 

 made by a method which enables us to ascertain the time curves of 

 respiration by determinations made at very brief intervals (in some 

 cases 1 minute or less). When the intervals are long (as in practi- 

 cally all previous investigations) it may happen that a rise in the rate 

 of respiration which is quickly followed by a fall cannot be detected; 

 and in general the form of the curve cannot be determined with 

 sufficient accuracy to enable us to study the dynamics of the process. 



Another point of importance is that so wide a range of material 

 was studied that it is possible to judge whether the results obtained 

 are of general vaHdity. The plants included bacteria, the higher 

 fungi, algae, and flowering plants, while the animals included insects, 

 frog eggs and tadpoles, and fish embryos. Precisely similar experi- 

 ments were made on all these forms and as these experiments were all 

 carried out under the same conditions the results are comparable in 

 all respects. 



