222 REPORT— 1851. 



to the comparative physiologist. The processes of preparation which the 

 food is required to undergo in its transit from the mouth to the blood may 

 not, and observation proves that it cannot be, divisible into the salivary, 

 gastric, biliary and pancreatic stages, in the humble invertebrate organism 

 as in the higher orders of vertebrated animals. The function of one secre- 

 tion is in reality merged into, and confounded with that of another, and that 

 in a manner which zoo-chemistry cannot yet explain. 



In the higher animals all proximate organic principles, such as albumeti, 

 fibrine, caseine and gelatine, from whatever source derived, must in the pre- 

 paratory processes, be first reduced to one common principle. Accordingly, 

 actual observation has i-epeatedly proved that the organic bases of chyme and 

 chyle consist of a soluble variety or phase of albumen. But in the lower 

 animal, if this object is accomplished at all in the digestive system, it may be 

 realized by the agency of some other products than phosphoric, hydrochlo- 

 ric or lactic acid and pepsin. In the higher animal the food first undergoes 

 the influence of the saliva, an alkaline fluid ; then that of the gastric juice, 

 an acid fluid ; and lastly, that of the biliary and pancreatic secretions, which 

 are alkaline again. In the Zoophytes and Medusae, the digestive and the 

 blood-making processes are conducted in one and the same system of chan- 

 nels. How striking the contrast when estimated by the standard of what 

 occurs in man ! The parietes of these channels may in some cases be or- 

 ganized such as to be capable of furnishing a secretion fitted to accomplish 

 the required changes in the vital and chemical composition of the contained 

 fluid. But observation, in many others, places beyond doubt the fact of the 

 absence of any such special organization in these parietes. In a memoir 

 recently submitted to the Royal Society, the author has recorded a large 

 mass of carefully collected evidence to prove that in invertebrated animals, 

 the circulating or nutrient fluids are charged in great profusion with highly 

 organized freely floating corpuscles; and that upon these moving-cells, and not 

 upon any parietal system of glands, the function 'devolves oi elaborating \h& 

 nutrient fluids — of raising them from a lower to a higher grade of vitality. 



The parietes of the cavities of the body and polypidom in Zoophytes ex- 

 hibit no glandular formations. The corresponding parts in the Medusae are 

 little less specialized in structure. And this is also the case with the Echi- 

 nodermata. In the Annelida, as already observed, the anterior half of the 

 alimentary canal is furnished with an order of glands, obviously distinguish- 

 able from that prevailing over the posterior moiety. The Crustacea present 

 a still further specialization of the glandular systems engaged in the element- 

 ary functions. Now, if in these several cases the digestive agency consist 

 essentially of a process by which heteromorphous principles are reduced to 

 one common principle, this object must be accomplished with a facility pro- 

 portionate to the simplicity of the animal's structure and its degradation in 

 the zoological scale : the chemistry of the humblest being becomes thus more 

 wonderful, because more vigorous, than tiiat of the highest animal. This 

 reasoning must be necessarily conjectural until facts whereon to rest it are 

 collected, to prove in what and how many respects the ultimate product of 

 the digestive chemistry, the finished blood, differs in difl^erent animals. In 

 the memoir quoted, the attempt has been made to demonstrate that in Zoo- 

 phytes, Medusae, Echinodermata, and the Annelida, sea-water is admitted 

 through the digestive organs directly into the midst of the nutritive fluids ; 

 that the latter possess therefore a power of assimilating, vitalizing, this ex- 

 traneous substance with a facility quite unknown in the higher animal. 



It has never yet occurred to the physiologist to consider that a " simpli- 

 city " iu the architecture of the solids of the animal body must iuvolve a 



