364 EXPEKIMENT STATION EECORD. 



the increase of the respiratory voluuie. While the efBciency, regarding the in- 

 dividually working muscle, reaches its maximum contemporary with the per- 

 forming maximum work, the efficiency for the ©rganism. as a whole, will reach 

 its maximum long before the muscle reaching maximum of the output of work. 



" Variations in the air pressure will influence the magnitude of the respi- 

 ratory level so that relative maximum points in the level curve correspond to 

 relative minimum points in the air pressure curve and vice versa ; thus a rise 

 or a sinking of the air pressure will involve a sinking or a rise of the respiratory 

 level respectively. 



" The respiration is reflectorily released with such an amount that the 

 carbonic acid percentage of the alveolar air is kept about constant. Should 

 any changes occur in the carbonic acid peix-entage of the alveolar air, the 

 respiration will at once appear with a new value, endeavoring to equalize 

 the changes. . . . 



" When closing the eyes the respiratory level goes down, and a simultaneous 

 decrease occurs in the carbonic acid eliminated and the oxygen absorbed ; these 

 changes being partly attributable to a less effective ventilation of the lungs. 

 The respiration of a subject resting, but awake, has a wavy course, but on 

 entrance of sleep the respiratory level is lowered, whereupon the respiration 

 elapses with a constant level value. The cause of the wavy respiration of the 

 subject, while awake and at rest, must partly be sought in changing states of 

 consciousness. 



"During the getting-by-heart of meaningless syllables, an increase of the 

 organic elimination- of carbonic acid occurred. This increase which is rela- 

 tively big at the beginning of the work, is partly attributable to a dilution of 

 the store of carbonic acid in the organism, but may besides, as a whole, be 

 understood as an expression for a contemporary increase of the production of 

 carbonic acid — consequently an increase of metabolism. A fraction of this in- 

 crease arises from the muscular movements performed during the mental work, 

 whereas the main part is due to psycho-physiological processes upon which the 

 association work depends. 



" The magnitude of the metabolic increase arising from mental work will 

 oscillate parallel to the subjectively estimated amount of work performed. 

 The metabolic increase attached to the performance of certain mental work 

 will gradually decrease, according as the subject acquires greater practice 

 in the work in question. Energetically the psychological notion ' concentration 

 of attention' will furnish an expression for the peculiarity that one may vol- 

 xmtarily solve the same problem in the same space of time with a various 

 amount of energy. The check occurring between contemporary energetical 

 transformation in the brain takes in the main the same course as corresponding 

 check effects in the case of simple physical motors." 



ANIMAL PRODUCTION. 



Further investig'ations into factors affecting the handling of wheaten hay, 

 including a study of its digestibility, A. J. Perkins, J. H. Phillips, W. J. 

 Spatford, and N. S. May (Jour. Dept. Agr. So. Aust., 17 (1914), No. 7, pp. 720- 

 755, figs. 3). — The results of 2 years' study at the Roseworthy Agricultural 

 College of the character and digestibility of wheat hay, cut in various stages of 

 development, indicate that maximum yields will be secured from cuts taken 

 about 3 weeks after full bloom at a time when the grain is just about to leave 

 the milky stage and enter upon the dough stage. 



It was noted that hay cut after the milky stage tends to become ill-balanced 

 hay, in which the culms and flag rapidly lose their feeding value, and if the 



