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TEXT-BOOK OF PHYSIOLOGY. 



spleen, it can not be said that any very definite results have been 

 obtained. The fact that the spleen can be removed from the body 

 of an animal without appreciably interfering with the normal metabo- 

 lism would indicate that its function is not^vej^^mportant^The 

 chief changes observed after such a procedufeare an enlargement 

 of the lymphatic glands and an increase in the activity oTtne red 

 marrow of the bones^-The presence of large numbers of leukocytes 

 in the splenic pulp and in the blood of the splenic vein suggested 

 the idea that the spleen is engaged in the production of leukocytes, 

 and to this extent contributes to the formation of blood. The 

 presence of disintegrated red blood- corpuscles has suggested the 

 view that the spleen exerts a destructive action on functionally 

 useless red corpuscles. These and other theories as to splenic func- 

 tions have been offered 

 by different observers, 

 but all are lacking posi- 

 tive confirmation. 



Volume Variations 

 of the Spleen. It was 

 shown some years since 

 by Roy, with the aid of 

 the plethysmograph, that 

 the spleen undergoes 

 rhythmic variations in 

 volume from moment to 

 moment. In the cat and 

 in the dog the diminu- 

 tion in the volume (the 

 systole) and the increase 

 in volume (the diastole) 

 together occupied about 

 one minute. 



This fact was determined by withdrawing the Spleen through 

 an opening in the abdominal wall and enclosing it in a box with 

 rigid walls, the interior of which was connected with a piston record- 

 ing apparatus. The system being filled with oil, each variation 

 m volume was attended by a to-and-fro displacement and a cor- 

 responding movement of the recording lever. The special form 

 of plethysmograph used for this purpose is known as the oncometer 

 or bulk measurer, and the recording apparatus as the oncograph 

 (Fig. 191 and Fig. 196). 



The cause of these .variations in volume Roy attributed to a 

 rhythmic contractility of the non-striated muscle-fibers in the capsule 

 and trabeculae, and not to changes in the arterial blood-pressure, 

 as the curve of the pressure taken simultaneously remained prac- 



FIG. 191. SPLEEN ONCOMETER LAID OPEN. 



