CIRCULATION IN SPECIAL PARTS 



The circulation in the mucous membrane of the mouth has been 

 examined by direct observation, while the volume of the "tongue can 

 be investigated with a suitable plethysmograph. By observing the 

 effects of section or excitation of the cervical and thoracic sympathetic 

 nerves during ophthalmoscopic examination of the eye in the curarized 

 rabbit, both vaso -constrictor and vaso-dilator nerves have been 

 ascribed to this organ, but the evidence in support of such nerves 

 is far from strong. 



The Salivary Glands. The vaso -constrictor fibres to the sub- 

 inaxillary gland issue from the first to the second or the second to the 

 third thoracic anterior roots, and pass up the cervical sympathetic 

 nerve. The cell stations for these fibres lie in the superior cervical 

 ganglion. 



The vaso-dilator fibres to the submaxillary gland pass by way of 

 the chorda tympani from the facial nerve, and have their cell stations 

 in contiguity with the gland. The vaso-dilator fibres to the parotid 

 gland issue from the glosso-pharyngeal nerve, and pass to the gland 

 by way of the auriculo -temporal nerve. The circulation in these 

 glands has been studied by placing a cannula in an efferent vein and 

 observing the outflow, or by exposing the gland and directly inspecting 

 its colour. 



The Circulation through the Limbs. By far the greater quantity 

 of the blood, 50 to 70 per cent., lies within the roomy reservoirs of 

 the abdominal and thoracic organs. From thence, by means of the 

 vase-motor mechanism, the blood is distributed to the locomotor 

 organs at need in times of activity. 



In the organs of locomotion, the quantity of blood during rest has 

 been roughly estimated to be 36 per cent., and during activity 66 per 

 cent., of the whole blood quantum. 



The blood-flow from the deep femoral vein of the dog during an 

 epileptic fit (excited by essential oil of absinthe) is three to five times 

 as great as during rest. The contraction of the muscles expresses 

 the blood which is within them on into the veins. 



Similarly, massage greatly increases the flow of blood through the 

 muscles. Massage of a considerable muscular area produces a fall of 

 general arterial pressure, in consequence of the deviation of blood 

 into the dilated muscular vessels. This fall may amount to one-fifth 

 of the initial pressure. Warmth also greatly increases the blood-flow. 



In the curarized animal the outflow from the muscular veins of 

 the lower limb is increased on excitation of the motor nerves. Vaso- 

 dilator fibres must run, therefore, in these nerves. On the other 

 hand, evidence of a diminished outflow on stimulation of the peripheral 

 end of the abdominal sympathetic has been obtained in the curarized 

 dog. We must therefore admit the existence of vaso-constrictor 

 fibres. They are, however, but poorly developed in the muscles. 



At times of great muscular effort a man closes his glottis, and holds 

 compressed his thorax and abdomen. By this means the intrathoracic 

 and intra -abdominal pressures are raised, the outlet from the veins 



