160 



42 7-5 - 203 



In the May experiments there is no definite order; the three 

 values must be considered as identical, as the difference between the 

 highest and the lowest is only 1 "/o of the average. 



When the average for the cold days is the same in May as in 

 April, in spite of the more advanced time of year and in spite of 

 the slightly higher temperature for the former, it must be remem- 

 bered, that there is no definite temperature at which the effect 

 begins, and that the low temperature is felt the more, the further 

 we are on in the spring. It is only in summer, when the epidermis 

 has become sufficiently thickened and pigmented, that a change 

 occurs in this regard. 



Bringing together what these 8 experiments show with regard 

 to the influence of the air-temperature on the respiration, we obtain : 



Frequency of the respiration decreases 



the alveolar CO o- tension increases 



the total volume of air respired diminishes 



the respiratory metabolism diminishes 



The increased carbonic acid tension in conjunction with the 

 diminished total volume of air respired indicates, that the excitabi- 

 lity of the respiratory centre is reduced, thus that the point of at- 

 tack of the "cold's influence" is the central nervous system itself. 

 It is not to be wondered at, therefore, that the "cold's influence" 

 indicated here is displayed in a manner which recalls the respira- 

 tion characteristic for hibernation. 



The daily period of the metabolism will appear from 

 the accompanying table, which embraces a double-series from No- 

 vember-December and one from May. The experiments were carried 

 out on different days; it was only exceptionally that two fell on the 

 same da}, never more. 



Owing to the uniformity which marks my series of experiments, 

 I consider such an arrangement as permissible. It then appears that 

 the four day-curves have the same form and only differ slightly 



