Scientific Proceedings. 



(ioi) 37 



sterilized without loss of radium, for the protective coat effectually 

 resists even continued boiling. The author demonstrated the radio- 

 activity of a strip of celluloid which had been coated with radium 

 and thereafter had been covered with collodion. The strip was 

 then placed in water in a test tube and the contents vigorously 

 boiled. Both the radium and the collodion solutions used for the 

 preparation of the coatings had been colored with a soluble blue 

 anilin dye. That the collodion protected the radium in this experi- 

 ment was shown by the fact that the water, after boiling, was entirely 

 free from color. The strip also retained its original radioactivity. 



The availability of the radium coatings for many kinds of bio- 

 logical investigation is so obvious that nothing need be said here 

 on that point. [See page 86 (150).] 



9 (55)- " Some of the physical phenomena of muscle fatigue," 

 with demonstration of tracings : FREDERIC S. LEE. 



The investigation of the subject has been continued by the 

 employment of a method by which the isotonic curves of all the 

 contractions of an excised non-curarized muscle stimulated at reg- 

 ular intervals, are superimposed upon a recording surface. The 

 differences which were previously pointed out in the mode of fatigue 

 of the muscles of the frog, the turtle and the mammal, have been 

 confirmed. Lohmann's work, in which a frog's gastrocnemius on 

 being heated to a mammalian temperature, shows a course of fatigue 

 similar to that of mammalian muscle, has been repeated and found 

 incorrect. Both that muscle and the turtle's coracoradialis pro- 

 fundus, similarly heated, continue to give their characteristic curves 

 of fatigue. [See page 60 (124).] 



Kaiser's method for determining the point of the isotonic curve 

 where the contractile stress terminates, has been employed for the 

 frog's gastrocnemius, and it has been found that as the height of 

 the curve diminishes in the course of fatigue, the contractile stress 

 terminates at progressively lower and lower points. The lowering 

 of the latter does not, however, seem to keep pace with the lower- 

 ing of the summit of the curve. Hence the two points seem to 

 approach one another. 



