160 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



ject's performance. These points were met, as described in the fol- 

 lowing paragraphs. 



As Dodge has pointed out, there is no limit to the number of reac- 

 tions that can be recorded on the same photographic plate, except that 

 beyond a certain number they will become confused with each other 

 and, on that account, illegible. It appeared to us that reactions, pho- 

 tographed on the plate at intervals of one-eighth inch, would be suffi- 

 ciently legible, provided the subject kept his head quiet in the head-rest. 

 Accordingly a device was arranged to move the Dodge falling-plate 

 camera laterally by small increments. See V, W, and T in figure 30, 

 also V in figure 41. A treadle T, shown in the lower left-hand corner 

 of figure 30 and worked by the operator's left foot, was kept in posi- 

 tion by a spring and connected to a pawl, which, when drawn down, 

 engaged with a toothed wheel at V. From the shaft on which the 

 toothed wheel was mounted a hght cord connected with the body of the 

 camera. When the wheel was turned to the left, therefore, the camera 

 was drawn to the left; the weight W kept the string taut and made the 

 movements to the left fairly easy. The camera was supported on two 

 slides which moved easily on the surface of the table. Usually the 

 camera was moved over one step for each reaction, unless it was neces- 

 sary to focus between reactions, when it was often moved two steps. 

 By this method of moving the camera it is not necessary to focus so 

 frequently as when the camera is moved by hand, which is usually a 

 rougher judgment. The device made it practical to take 15 or 16 

 reactions on one plate 2| by 7 inches in size. The camera could be 

 moved freely right and left when the operator's foot was not on the 

 treadle, T. 



In beginning to take records on a plate the camera was moved to the 

 right, and the beam of light from the subject's eye focused on the 

 glass G, below the plate P, and at a position indicated by the small cross. 

 (In the Dodge camera the arrangement which holds the plate-holder 

 containing the photographic plate, P, moves downward with the flow of 



Explanation of Figure 30. 

 F, focusing hood of camera; G, ground glass focusing screen; B, by-pass oil cylinders; P, photo- 

 graphic plate in frame which moves downward with the flow of oil ; S, shutter to expose P, 

 opened by cord, 1, when P is completely raised and closed by cord, 2, at the completion 

 of the fall of the plate; C, sliding contact operated by the movements of the plate-holder; D, 

 drip-pan for oil; T, foot treadle operating a pawl on a toothed wheel at V by which the 

 whole camera is moved short distances to the left for successive eye reactions ; W, weight 

 to keep taut [the cord connecting the camera to V; X, strings by which the experimenter 

 may operate the exposure apparatus not shown in this figure. 



Explanation of Figure 31. 



All three measurements employed the Blix-Sandstrom kymograph. See fig. 28 for wiring diagram. 



i'', position of foot when recording patellar reflexes; B, light wooden bar, the right end of which 

 rests against patellar tendon; H, pendulum hammers which, when released by the electro- 

 magnets, M, fall against B and produce stimulus for reflexes ; ;S, movable base carrying the 

 frame for M and H adjustable to height for different subjects by 1, 2, and 3; A, adjustable 

 connection between quadriceps muscle and recording lever. E, exposure apparatus for 

 word reactions in position clamped to post, P; W, window in which the words appear; V, 

 voice key for reaction of subject. 



