202 



instances observed to be accomplished by the most simple. 

 Enough, however, of this. 



5. Another theory which has been proposed in explanation 

 of the use of the spleen is, that it is a viscus to which a large 

 volume of arterial blood is sent, for the purpose merely of its con- 

 version into venous blood; that the object of this conversion is to 

 supply to the liver an adequate quantity of that blood from which 

 bile is secreted. This theory is perhaps ^better supported by per- 

 ceptible occurrence than the last j the blood from the splenic vein 

 certainly goes to the liver, and if bile is secreted, as is from other 

 circumstances made probable, from venous blood, then the spleen 

 must have a function of this kind by which it is related with the 

 office of the liver. These theories, perhaps, may, either singly 

 or both together, make up the tru account of the use of the 

 spleen. That it is not a secretory organ is obvious: we have 

 therefore, in considering its vital properties, to determine only 

 concerning the laws of those which belong to a structure made up 

 of arteries, veins, nerves, membrane, &c.; exhibiting, either in- 

 dividually or collectively, no function which is not every where 

 common to these components of the textures. 



6. According then to the analogy of the mixed structures, 

 and according to the test of division, which has already been 

 sufficiently spoken of, we should at once decide that the life of the 

 spleen is simply of the assimilating kind. The only manifest con- 

 version of fluid which .takes place in it is that of arterial into 

 venous blood; a process/which goes on alike in the paralytic 

 limb, or in one, the nerves of which havse been divided, and in 

 that whose animal character is entire. 



7. If, then, the spleen can scarcely be suspected to be related 

 with the preparatory processes, in- any except the subordinate way 

 suggested by the preceding theories; if such is the only way in 

 which it concurs mediately with the digestive organs ; it is next to 

 be inquired, if it contributes directly, by a relation with the 

 spiritual properties of adjoining structures, to the common end? 

 In answer to this question, it need only be reoiarked that we are 

 precluded the precise analytical and synthetical tests in examining 

 relations of this kind. We can merely ascertain the existence of 

 such .a relation, and we infer it when regular phenomena are modi- 

 fied, or made to cease by intercepting communications between 

 parts, and when there is no reason to suspect a mediate relation, 

 established by the intercourse of fluids. Hence, as the spleen has 

 been removed, with no other eiFect or influence of. the direct kind 

 than that which might be supposed to arise .rather from the in- 

 fliction of an injury than from the privation of accustomed pro- 

 perties, we possess no evidence by which a relation of this sort 

 may be established in the present instance.; .Indeed the fact just 

 cited proves, that if the spleen, has any use. at all, it is not worth 

 inquiring after; a sufficient ground for dismissing it from: our 

 present consideration. 



