178 



Scientific Proceedings (39). 



casein was heated at 8o° with 20 per cent, hydrochloric acid. In 

 this case, hydrolysis was complete in ten hours, the amino nitrogen 

 having reached its maximum, 71 per cent, of the total. 



113 (523) 



A demonstration of Krogh's micro-tonometer for the determi- 

 nation of gas tensions in fluids. 



By M. M. SCARBOROUGH. (By invitation.) 



[From the Physiological Laboratory, Department of Medicine, Yale 



University.] 



The advantages of Krogh's apparatus are, first, the small 

 amount of fluid required; second, the large specific surface ob- 

 tained; third, the rapidity and accuracy of determinations. The 

 bubble of gas used is about 2 mm. in diameter, having a specific 

 surface of 30 as compared with a specific surface of 3.3 in Pfliiger's 

 aerotonometer, 5.2 in Bohr's hemataerometer and 3.7 in Fred- 

 ericq's. A fine spray of the fluid to be examined is played on the 

 bubble for a few minutes; the bubble is then drawn into a capil- 

 lary burette where it is measured before and after the absorption of 

 oxygen and carbon dioxide. For carbon dioxide alone in fluids, a 

 very simple vessel is used; the tonometry is accomplished by 

 shaking a small bubble of air with a relatively large amount of fluid. 

 The bubble is then transferred to the capillary burette and 

 analyzed. The limit of error can be brought down to +0.2 per 

 cent. 1 



1 14 (524) 

 Breeding experiments in poultry. 



By H. D. GOODALE. (By invitation.) 



A. Note on the Results of a White Leghorn by White Plymouth 

 Rock Cross. 



The cross was made in only one way, viz., white Leghorn 

 females X White Plymouth Rock males. The chicks were white 

 with sometimes a few black spots. They developed into white 

 birds, with a few black spots. Later the surface color became 



'For full description of apparatus and methods see Krogh's articles in Skan- 

 dinavisches Archiv fiir Physiologic 1908, xx, 259-288. 



