Society for Experimental Biology and Medicine. 



course of two months, seven were reported negative and twenty 

 positive. Of the seven negative cases, six proved to be certainlv 

 not typhoid, and one was very doubtful. Excluding the doubtful 

 case, there is a record of 100 per cent, in cases ranging from the 

 fifth to the nineteenth day. By means of litmus-lactose-agar plates, 

 reports can be made in 24 hours with a fair degree of certainty. 

 After incubating the bile-blood over night, streaks are drawn over 

 the plates, and in 5 or 6 hours a growth may be visible. If the 

 growth prove to be a bacillus which reacts to a microscopical Widal 

 test the case is reported positive. 



3 (146) 



The inconstant action of muscles. 

 By WARREN P. LOMBARD and F. M. ABBOTT. 



[From the Physiological Laboratory of the University of Michigan^ 



The movements of the hind leg of the frog which are gener- 

 ally ascribed to finely adjusted nervous coordination, are in fact 

 largely the result of the mechanical conditions under which the 

 muscles act. These conditions differ with each new position of 

 the bones entering into the joints of the limb, and consequently 

 alter the effects of the contractions of muscles as the positions 

 of the bones change during the course of any given movement. 

 Thus a muscle which in one position of a bone may act as a flexor, in 

 another position may act as an extensor, and a muscle which in one 

 position of a bone may carry it dorsally, in another position may 

 carry it ventrally. Manifestly it is absurd to try to class muscles 

 as flexors and extensors, for example, or to try to name them 

 according to the movement which they are supposed to produce. 

 Nor can one, without qualification, speak of certain muscles as 

 antagonists, when under slightly modified conditions of action 

 they act as synergists. Moreover, it is evident that we can form 

 no estimate of the part played by the central nervous system in 

 coordinated movements of locomotion, for example, until we have 

 ascertained in how far the coordination observed is due to the 

 mechanical conditions under which the muscles are acting. A 

 study of central coordination must, in short, be postponed until 



