740 TRANSACTIONS OF SECTION K. 



The somewhat variable results and some hitherto unrecorded sudden varia- 

 tions made it seem desirable to investigate anew into the phenomena involved. 



It ■will be seen that the Avork was not a repetition of that of Kraus and 

 Garreau, as it involved the direct estimation of the gaseous interchange ; both 

 COj and O5 (no other gases being demonstrated) were simultaueously ascertained. 

 This was possible with Dr. Haldane's apparatus for gas analysis.' This part of the 

 work was done under his guidance. 



The temperature was ascertained by two methods ; for the ordinary rise the 

 surface temperature was taken with a number of delicate thermometers (five) which 

 could be read together within the required range ; they were graduated to tenths 

 of a degree Centigrade. Further data as to internal temperature and local oscilla- 

 tions were obtained with the thermopile. 



It was difficult to obtain the necessary material in sufficient quantity ; the 

 Cambridge Botanic Garden furnished a number of valuable samples, which made 

 it possible to give some details of heat-rise in three species not formerly experi- 

 mented with — Helicodiceros Tmiscivorum, Arum elonffatum, Colocasia antiquorum, 

 var. Fontanesii — as well as A. italicum, A. maculativtn, and 1). vulgaris. 



The whole work was carried out in the Oxford Physiological Laboratory, owing 

 to the kindness of Professor Gotch, who himself directed the work. 



jResults. — The supposition that no truly normal results of gaseous interchange 

 are to be expected in experiments carried on in confined air seems to be confirmed 

 by the fact that a current of air falling below a minimum of 30 cc. per minute 

 produced sudden depressions of the rising temperature. Further, the sensitiveness 

 of the plant at this time was seen in the sudden local rise of temperature on 

 wounding — -2° C. to '35° C. (conducted upwards as much as 5 to 6 mm.), with a fall 

 lasting over three to seven minutes ; and, further, in the fact that no plant under 

 experimental conditions showed the maximal rise as compared with outdoor 

 specimens. 



The diurnal recurrence of heat production was noted only in a few specimens 

 of A. maculatum and of D. vulgaris. In A. italicum it appeared only associated 

 with an artificial disturbance of the process of starch combustion. The gaseous 

 interchange seems to follow exactly the rise and fall of the local heat production, 

 which appears to be quite independent of external temperatures (within normal 

 limits) or of light, and coincides with the protrusion of the sligmatic hairs. 



The maximum rise of the gaseous interchange is rapidly attained, the highest 

 noted being a production of 2-97 cc. of COo, with an absorption of 3'08 cc. of 0^ 

 (calculated at 766 mm. mercury pressure 0° C). 



The respiratory quotient varies considerably, but except after the first sudden 

 drop in the gaseous interchange is always less than 1 ; at that point in some cases 

 respiratory quotient 1, or even 1-2, has been noted. Over the subsequent slow 

 subsidence of the interchange more 0.^ is again absorbed. 



Extracts from the spadices of three species gave indications of the presence of 

 a number of enzymes ; it is intended to investigate these as soon as material is 

 available. 



Report on the Registration of Botanical Photographs. 

 See Reports, p. 433. 



G. Report on Peat Moss Deposits, — See Reports, p. 430. 



See Journal of Hygiene, January 1906. 



