iS4 Dr. T. Williams on the Mechanism of Aquatic 



duce mechanical results, Contemporaneonsly with this system 

 accordingly appears the dermal skeleton of these classes. It is 

 quite certain that such a highly developed state of the muscle- 

 system as that which exists in the articulated animal implies of 

 necessity* the presence of a considerable proportion of fibrinc in 

 the blood. The production 'of ^in'n^ in the fluids supposes a 

 high standard of respiration, and a correspondently developed 

 nervous system. 



■'*''0f these several events, which takes the lead ? Is it possible 

 that an increase in the complexity of solid systems, the integu- 

 mentary, the nervous, and the muscular, can go before the 

 increasing complexity which occurs at this stage in the zoological 

 series in the composition of the fluids ? The question involves 

 the absurdity of conceiving an effect without a cause, a sequence 

 without an antecedence. Nature makes fii'st the mortar, then 

 builds ; the fluids are first prepared, then the superstructure of 

 the solids is raised. 



The function of respiration always, in every animal, is insepa- 

 rable from the blood-making physiological actions. It is com- 

 monly supposed that it is with the system of the fluids that the 

 office of breathing immediately connects itself. Extraordinary 

 facts will be afterwards adduced which wall render this suppo- 

 sition no longer exclusively tenable. The tubular apparatus of 

 the fluids evolves itself at some point or other of its periphery, 

 such that the amount of oxygen received shall be proportional, 

 not to the abstract bulk of that fluid, but to its vital compo- 

 sition. A veiy small vertebrated animal weighing fivefold less 

 than a given invertebrated animal, will consume in equal times 

 fiftyfold more oxygen than the latter. ' Respiration,^ therefore, 

 is not an isolated physiological act, separable physically and 

 dynamically from that complex assemblage of events which con- 

 spire in the maintenance of the living organism : it is an in- 

 teger in the arithmetic sum of life. Its real value can only be 

 determined by a study of it in its connections. Given the vital 

 and chemical composition of the fluids, to estimate the propor- 

 tion of oxygen demanded by any appointed organism ? The 

 problem is not empirical ; it is scientific in the highest degree. 

 It is an absolute rule in the physics of organization, that the 

 structure and the function are directly proportional. An im- 

 perfect instrument can only produce imperfect results. The 

 complex fluids and highly organized solids of the articulated ani- 

 mal render indispensable the provision of an adequate machinery 

 for the inhalation of the vivifying principle. Thus then are 



* See the author's papers " On the Blood," now being published in the 

 British and Foreign Meaical and Chirurgical Review, for a full exposition 

 of thi« subject. 



