32 PHYSICS OF STREAMING 



taining well-aerated water, which was then covered by a layer of oil. 

 By means of a syphon-tube measured volumes of the water were drawn 

 off at stated intervals and run into a titrated solution of barium hydrate. 

 The clear liquid from the latter was then titrated with oxalic acid, using 

 phenolphthalein as an indicator. By means of a side tube connected 

 with the long arm of the syphon, reduced indigo solution could be added 

 to the issuing water, and the presence or absence of free oxygen in it 

 detected. The experiments were continued until no free oxygen was present. 

 On reducing the results to terms of a single cell it was found that 

 0-754 cubic mm. of protoplasm, of which 0-47 1 were actively streaming, 

 produced a maximal amount of 0000336 to 0-000472 mgr. of CO 2 at 18 C. 

 In another case 0-14 to 0-08 mgr. of CO 2 were produced at 17-5 C. per 

 gramme of plasma per hour, whereas actively respiring tissues of 

 Phanerogams may evolve per gramme of plasma from 0-2 to 2-0 mgr. of 

 CO 2 per hour. Rotation continues in Chara even when the surrounding 

 water contains no free oxygen, i. e. when the production of carbon dioxide 

 sinks to from | to T ^ of the above values. The theoretical consumption 

 of energy in producing streaming in a cell of Chara or Nitella (p. 27) 

 represents less than o-oooi per cent, of the total energy of active respira- 

 tion, and hence only a fractional amount is utilized for streaming, even 

 when respiration is at its lowest ebb. Further, the production of carbon 

 dioxide is not a perfectly safe guide as to the amount of energy 

 liberated by katabolism, since this must largely depend upon whether 

 proteids, carbohydrates, or fats are consumed in respiration, as well as upon 

 the amount and character of the by-products. Moreover, katabolism need 

 not always lead to a production of carbon dioxide, and the latter may 

 even involve an absorption instead of a liberation of energy, viz. decompo- 

 sition of oxalic, citric, and malic acids. In all cases the values obtained 

 for the consumption of energy in streaming are the minimum possible for 

 this particular function on the assumption that the motor-mechanism is 

 a perfect one. Since, however, certain other functions must always coexist, 

 the net consumption of respiratory material must always be very much 

 greater than this. Moreover, the protoplast appears to be a very im- 

 perfect machine, for Rodewald * has shown 'that, as far as calculations 

 based upon the production of carbon dioxide can be relied on, by far 

 the greater part of the energy of respiration appears in the form of heat 

 by conduction, radiation, and evaporation. We may regard the protoplast 

 as a machine capable of performing several different kinds of work 

 simultaneously, but never exercising its full potential capabilities in all 

 of them at the same time, and usually all being carried out below their 



1 Jahrb. f. wiss. Bot., 1889, xx P- 2 75- I" 1 one case 22 grams of Kohl-rabi evolved at 

 20 C. 0-6070 gram of CO a in 59 hours, and lost 70 calorics per hour. 



