CONTRACTION OF THE SPLEEN. 



209 



digestion are partially acted upon in the spleen, and undergo further 

 change in the liver.] 



There is a relation between the size of the spleen and that of the 

 liver, for it is found that when the spleen contracts e.g., by stimulation 

 of its nerves the liver becomes enlarged as if it were injected with 

 more blood than usual (Drosdow and Botschetschkarow). 



[Oncograph. Botkin, and more recently Roy, have studied various 

 conditions which affect the size of the spleen. Roy's observations 

 are most important. He enclosed the spleen of a living animal (dog) 

 in a box with rigid walls, and filled with oil after the manner of the 

 plethysmograph ( 101). Any variations in the size of the organ 

 caused a variation in the amount of oil within the box, and these 

 variations were recorded. This instrument Roy termed an " ONCO- 

 GRAPH" (oyxoc, volume). The blood-pressure was recorded at the 

 same time. 



Roy finds that the circulation through the spleen is peculiar, and 

 that it is not due to the blood-pressure within the arteries, but is 

 carried on chiefly by a rhythmical contraction of the musculaf fibres of 

 the capsule and trabeculse. The spleen undergoes very regular rhyth- 

 mical contractions (systole) and dilatations (diastole). This alternation 



Fig. 91. 



Tracing of a splenic curve, reduced one-half, taken with the oncograph. The upper 

 line with large waves is the splenic curve, each ascent corresponds to an 

 increase, and each descent to a diminution in the volume of the spleen. The 

 curve beneath is a blood-pressure tracing from the carotid artery. The lowest 

 line indicates the time, the interruptions of the marker occurring every two 

 seconds. The vertical lines, a and 6, give the relative positions of the lever 

 point of the oncograph, and of the point of the recording style of the kymograph 

 respectively (Roy). 



