244 THE CELL-THEORY 



anatomical, and developmental inquiries, still it is clear, that if the 

 above account of the correlation of these branches of science be 

 correct, their logical connexion, and the order, therefore, in which 

 they must eventually arrive at perfection, is precisely the reverse. 

 The striking and mysterious character of many of the functions may 

 have led to the study of structure ; but assuredly the understanding 

 of the former presupposes a thorough knowledge of the latter. 



It is conceivable that structure might be thoroughly made out 

 without the least acquaintance with function, just as the ancient 

 anatomists were well acquainted with the construction of the muscular 

 system, and yet had no suspicion of its being the motor apparatus, 

 and as at the present day we know full well the structure of the 

 " vascular glands," though we can but guess their purpose ; but it is 

 quite impossible to attain to a complete knowledge of function without 

 a thorough anatomical analysis. The action of the whole of any- 

 organ depends upon and is, that of the sum of its parts ; it is, 

 mechanically speaking, their resultant ; so that until the nature and 

 the precise modes of operation of all these parts have been made out, 

 we can have no security that any law propounded concerning the 

 functions of the whole, is other than a mere empirical generalization, 

 liable to be interfered with at any moment, by the properties of some 

 of the elementary parts with which we are unacquainted. Thus, up 

 to within a few years ago, contractility was affirmed to be a general 

 property of the cellular tissue of the skin ; and this would have 

 remained as an ascertained law, had not Kolliker shown, by the 

 discovery of the extensive distribution of muscular fibre in it (that is, 

 by pushing anatomical analysis a step further than it had previously 

 been carried), that the supposed law was but an empirical generaliza- 

 tion, and that the property of contractility, supposed to be inherent 

 in the ordinary connective tissue of the skin, was, in fact, deducible 

 from the presence of a totally different structure. 



So again, Haller and his followers quoted the contraction of the 

 heart, when removed from the body, as evidence of the innate contrac- 

 tility of muscle, apart from all nervous influence. This vis insita may 

 exist or it may not, but further anatomical investigation has at any 

 rate destroyed the force of the argument, by demonstrating the 

 existence of nervous ganglia within the substance of the organ. 



But enough of illustration of what must be sufficiently plain to 

 any one who will reflect upon the subject ; namely, that however much 

 might be done towards the establishment of broad physiological 

 truths, while the knowledge of structure was in a rough and imperfect 

 state, still an exhaustive study of structure is absolutely necessary, 



