CH. XXIII.] SPLENIC WAVES 333 



divided nerves, e.g., vagus and sciatic ; (3) by local stimulation by an 

 electric current ; (4) by the administration of quinine and some other 

 drugs. 



It has been shown by the oncometer (see p. 308) that the spleen 

 undergoes rhythmical contractions and dilatations, due to the con- 

 traction ;and relaxation of the muscular tissue in its capsule and 

 trabeculse. A tracing also shows waves due to the rhythmical alter- 

 ations of the general blood-pressure. Fig. 311 is a typical tracing 

 obtained by Schafer's air oncometer from a dog's spleen. 



It shows, first, the large waves occurring about once a minute, 

 duel to the splenic systole and diastole; secondly, smaller waves on 



FIG. 311. The upper tracing is the spleen record ; the uext is carotid blood-pressure taken with a 

 mercurial kymograph. The straight line beneath this is the abscissa of the arterial pressure ; and 

 the lowest tracing is the time in seconds. 



this, due to the effect of respiration on the blood-pressure ; and on 

 these, smaller waves still, corresponding with the individual heart- 

 beats. The large waves due to the splenic contractility still go on 

 after the division of all the splenic nerves. These nerve-fibres leave 

 the spinal cord in numerous thoracic anterior roots ; they have cell 

 stations in the sympathetic chain (Schafer) or semi-lunar ganglia 

 (Langley). 



Hsemolymph Glands. 



The existence of glands which partake of the nature of the spleen, 

 and of lymphatic glands, has long been known. They have been 

 recently more fully investigated by T. Lewis. He finds them in 

 most mammals, and they can be readily distinguished from ordinary 



