152 INFLUENCE OF NERVES ON THE SPLEEN. 



of the plethysmograph ( 101, 276). Any variations in the size of the organ 

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

 recorded. The blood-pressure was recorded at the same time. The circulation 

 through the spleen is peculiar, and is not due to the blood-pressure within the 

 arteries, but is carried on chiefly by a rhythmical contraction of the muscular 

 fibres of 'the capsule and trabecular The spleen undergoes very regular rhyth- 

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

 and diastole may last for hours, and the two events together occupy about one minute 

 (fig. 124). Changes in the arterial blood-pressure have comparatively little in- 



Fig. 124. 



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 b, give the relative 

 positions of the lever-point of the oncograph, and of the point of the recording style of the 

 kymograph respectively {Roy). 



fluence on the volume of the spleen. The rhythmical contractions, although 

 modified, still go on after section of the splenic nerves. This would seem to 

 indicate that the spleen has an independent (nervous) mechanism within itself, 

 causing its movements.] 



[Influence of Nerves. Section of the splenic nerves is followed by an increase 

 in the size of the spleen. The nerves have their centre in the medulla oblongata. 

 Stimulation of the medulla oblongata, either directly or by means of asphyxiated 

 blood, causes contraction of the spleen, hence the spleen is " small and contracted " 

 in death from asphyxia. The fibres proceed down the cord, and leaving it in the 

 dorsal region, enter the left splanchnic, pass through the semi-lunar ganglion, and 

 thus reach the splenic plexus. Stimulation of the peripheral ends of these nerves 

 causes contraction of the spleen, and so does cold applied to the spleen directly or 

 over the region of the organ. In the last case the result is brought about reflexly. 

 Botkin found that the application of the induced current to the skin over the 

 spleen, in a case of leukaemia, caused well-marked contraction of the spleen in all 

 its dimensions, and the result lasted some time. After every stimulation the 

 number of colourless corpuscles in the blood increased, and the condition of the 

 patient improved.] 



[There is a popular notion that the spleen is influenced by the condition of the 

 nervous system. Botkin found that depressing emotions increased its size, while 



