44 THE MENDEL JOURNAL 



defined from those of others, and that the gametic 

 composition of these individuals is in accordance with 

 a Mendelian conception of alternative unit characters. 

 In the laboratory it is not difficult to demonstrate, 

 either on the living subject, or by electrical stimulus 

 applied directly to excised muscle, or indirectly 

 through its nerve, the amount of work a particular 

 muscle is capable of performing before fatigue is 

 induced. In man muscular fatigue can be directly 

 measured by means of an ergograph. By this instru- 

 ment a record of successive contractions repeated 

 at regular intervals, say of one of the flexor muscles of 

 the finger in raising a weight, is taken on a revolving 

 drum. So long as the muscle is working within its 

 capacity, no alteration is observable in the successive 

 curves traced out ; but, when the muscle becomes at 

 all fatigued, the diminished height of contraction is 

 at once indicated on the drum. The actual amount 

 of work which the muscle can perform at a given 

 frequency of stimulation before fatigue is induced is, 

 of course, obtained by multiplying the weight by 

 the total distance through which it is raised. This 

 method of testing muscles and measuring their work 

 is really only applicable when the subject brings 

 intelligent co-operation into play. It is inapplicable 

 to the horse, and, more particularly, to the thorough- 

 bred horse. Then, too, there is the serious drawback 

 that the behaviour of only a few muscles can be 

 studied, whereas what is really required is a record 

 of the amount of work performed in a given time in 

 executing a series of co-ordinated and strenuous 



