310 THE VITAL FUNCTIONS. 



marvellous transformations, far surpassing even 

 those which the most visionary alchemist of former 

 times had ever dreamed of achieving? Questions 

 like these can be fairly met only by the confession 

 of profound ignorance ; for, although the subject 

 of secretion has long excited the most ardent 

 curiosity of physiologists, and has been prosecuted 

 with extraordinary zeal and perseverance, scarcely 

 any positive information has resulted from their 

 labours; and the real nature of the process remains 

 involved in nearly the same degree of obscurity as 

 at first.* It was natural to expect that in this 

 inquiry material assistance would be derived from 

 an accurate anatomical examination of the organs 

 by wliich the more remarkable secretions are 

 formed ; yet, notwithstanding the most minute and 

 careful scrutiny of these organs, our knowledge of 

 the mode in which they are instrumental in effect- 

 ing the operations which are there conducted, has 

 not in reality advanced a single step. To add to 

 our perplexity we often see, on the one hand, parts, 

 to all appearance very differently organized, giving 

 rise to secretions of a similar nature ; and on the 



* It is not yet precisely determined to what extent the organs of 

 secretion are immediately instrumental in producing the substance 

 secreted ; and it has been even suggested that possibly their office 

 is confined to the mere separation, or filtration from the blood, of 

 certain animal products, which are always spontaneously forming 

 in that fluid in the course of its circulation. This hypothesis, in 

 which the glands, and other secreting apparatus are regarded as 

 only very fine strainers, is supported by a few facts, which seem 

 to indicate the presence of some of these products in the blood, 

 independently of the secreting processes by which they are usually 

 supposed to be formed ; but the evidence is as yet too scanty and 

 equivocal to warrant the deduction of any general theory on the 

 subject. 



