july — sept. 1857.] between the Animal and Plant. 179 



endesmose the elements of nutrition, which thus pass in their crude 

 state into the general circulation, where they are elaborated and 

 fitted for their future destiny. In the vertebrate animal, the lac- 

 teals already referred to terminate by looped extremities amongst 

 a number of cells and nuclei ; and during the passage of chyme 

 along the intestine these nuclei become developed into cells, and 

 the cells are busy at work selecting, absorbing and elaborating, and 

 then yielding up their contents to the loops of the lacteals. In 

 plants the root is the great organ of absorption, whether suspend- 

 ed in air, floating in water or buried in the earth. The root con- 

 sists of a cellular epidermis, and internal structure of vascular bun- 

 dles and cells. Here then cells are still the great organs of ab- 

 sorption, and if we trace the sap upwards through the alburnum and 

 leaves, and its return through the lactiferous vessels and cells of 

 the bark, we shall find them not less active and essential in the 

 process of assimilation. If we now review the function of respira- 

 tion in the animal and plant, we shall find that although by this 

 process the animal eliminates carbon and consumes oxygen, while 

 the plant fixes the former and gives off the latter, being thus so far 

 opposed in object, they nevertheless agree inasmuch as respiration 

 is carried on in both kingdoms, by means of organs of a cellular 

 structure. In both too the ultimate objects of the function are the 

 alteration and refinement of the circulating or nutritious fluid, the 

 blood in the one and the sap in the other being fitted for the pro- 

 duction of new or repair of old tissues, and for keeping up a sup- 

 ply of the various secretions. Respiration is therefore a depura- 

 tory process, and perhaps the least vital of any of the functions of 

 organic life, many of the changes it effects being merely the results 

 of a chemical action. We come now to speak of secretion, which 

 is carried on by means of certain cellular organs called glands. 

 These appropriate each a definite nature of material from the cir- 

 culating fluid, as it passes along fertilized by the results of absorp- 

 tion and assimilation. Besides their nutritious elements however, 

 the blood and sap contain unorganizable substances the effete pro- 

 ducts of tear and wear, which are separated to be excreted by 

 glands differing in no important particulars from those already 

 mentioned. The individual cells concerned in the manufacture of 



