WORK OF THE PHYSIOLOGICAL STATION AT PARIS. 401 



curvature of the ribs, the unequal tlexibility of their cartilages, and 

 their multiple articulations both with the bodies and transverse proc- 

 esses of the vertebrte aud with the sternum and costal cartilages. 

 Without points of reference observation of the movements of the ribs 

 was absolutely impossible; the nature of these displacements has there- 

 fore been heretofore determined according to certain theoretical con- 

 siderations. Experimentation gives, on the contrary, very exact results. 



A series of small, black rods (fig. 1, plate XLIX) presses loosely upon 

 the walls of the chest, each resting upon a rib by one of its extremities 

 and bearing near this point a very brilliant pearl. An ordinary photo- 

 graphic apparatus is turned toward the subject of experiment, who, 

 strongly illuminated, is placed before a black background. If the 

 exposure lasts during the entire respiratory movement we obtain fig. 1, 

 in which each of the brilliant pearls has traced the movement of the 

 subjacent rib. At the first glance it is seen that each rib has its own 

 special movement. 



This is not the place to analyze the mechanism of this movement. I 

 may say, however, that among the divers opinions which have been 

 held by authors that of Chabry accords the best with the results of the 

 experiments. 



If it is required to know the nature of the movement of the anterior 

 wall of the chest, we apply upon that wall the series of rods and obtain 

 the trajectory of each of the points of that wall from the epigastrium to 

 the superior part of the sternum. We then see that the epigastrium 

 has but a slight upward movement, while the sternum moves obliquely 

 upward and forward. 



Similar researches repeated upon dilierent species of animals would 

 doubtless give interesting results as to the comparative i^hysiology of 

 respiration considered from a mechanical point of view. 



Another very important study is that of respiratory types. It has 

 been supposed that women breathe especially by means of the upper 

 part of the thorax (superior costal type), and men by the diaphragm 

 (abdominal type). Hutchinsou has shown these two types by tracing 

 on a wall the silhouette of a man and that of a woman in the two 

 extreme states of inspiration and expiration. But the hand has not 

 time to trace the profile of the thorax and of the abdomen during the 

 few instants in which inspiration reaches its extreme limits 5 besides, if 

 the subject stops his respiratory movements a moment, nothing x)roves 

 that the thorax and the abdomen keep the res^iective positions which 

 they had in normal resj^iration. 



Photography replaces with advantage the tracing of the silhouettes. 

 An ordinary apparatus provided with a pneumatic shutter is trained 

 upon the subject. A picture is taken during inspiration, another dur- 

 ing expiration, and we thus obtain a double contour for all parts of the 

 trunk displaced. W^e thus show that in a woman without a corset 

 respiration occurs as it does iu a man — that is to say, that the thorax 

 aud tlie abdomen both take piart in it. 

 SM 1)4 26 



