The Control of Respiration. 



253 



gel dried down to less than 3 per cent, moisture content had 

 imbibed at the end of 72 hours 6.45 grams of water per gram dry 

 gelatin as contrasted with 4.30 grams water for a 40 per cent, 

 gel similarly treated. Comparable differences were observed when 

 the dried sheets were ground and uniform sized particles sieved 

 out and tested for hydration rate and maximum hydration capac- 

 ity. 



Our experiments indicate that gelatin gels have a structure 

 and that this structure is fixed at the time of gelation and is not 

 appreciably altered by drying the gel at room temperature. A 

 crystal structure in which the gelation temperature is actually the 

 melting point of the crystals would explain the peculiarities ob- 

 served. 



112 (1859) 

 The control of respiration. 



By C. C. GAULT and F. H. SCOTT. 



[From the Department of Physiology, University of Minnesota, 

 Minneapolis, Minn.] 



The movements of respiration are carried out by voluntary 

 muscles and ought to obey the laws of voluntary movement. One 

 of the chief points in muscular action is the dependence of motor 

 response on sensory impulses. Without the guidance of sensory 

 impulses movements are ataxic. Just how ataxic or abnormal 

 movements become depends on the extent of loss of sensory im- 

 pulses and on the ability of the mechanism to guide itself by sen- 

 sory impulses from other sources. These statements hold true 

 in regard to the movements of respiration. It has long been 

 known that a modified respiration results from cutting off the 

 sensory impulses from the lungs by section of both vagi. Many 

 investigators have, however, kept animals with divided vagi so 

 that one cannot maintain that the vagi are essential to respiration. 

 However, it was pointed out by one of us 1 a number of years ago 

 that animals with vagi divided are not nearly as efficient in times 

 of respiratory stress as is a normal animal. It was shown by 



1 Scott, F. H., Jour, of Physiology, 1908, xxxvii, 301. 



