MUSCLES AND NERVES 



135 



2. Muscles and nerves. The rate of movement in flight 

 (Dubois, '98), for example, may be due in a measure to the short 

 nerves, or the rapidity of metabolic change in muscles, or to both. 



When the gastric end of a duodenal segment is taken some 

 fifteen hours after the last feeding from a healthy male rat 80-200 

 days of age, and when the animal has been for at least three days 

 in the transfer cage, and is also carefully handled and anaes- 

 thetized without undue excitement, the response of the segment 



TABLE 91 



Showing the content of total nitrogen as well as non-protein nitrogen in the entire 

 brain of the albino rat at different ages 



to sodium carbonate solution is fairly regular (Hatai and Ham- 

 mett, '20). Segments from females should not be used. 



Working with duodenal segments thus standardized, Hammett 

 ('2 la) found that in response to the stimulation by 0.1 M sodium 

 carbonate, the segment gave nearly uniform contractions. In 

 66 per cent of the observations the deviation was plus or minus 

 5 per cent, and in 90 per cent of the observations, plus or minus 

 10 per cent. 



Hammett ('21 b) concludes that the intestinal mechanism 

 primarily stimulated when sodium carbonate is thus applied to 

 the isolated duodenal segment of the rat is neural and not mus- 



