Animal Morphology. 79 



or definite chemical compounds to adapt it for the changed 

 differentiation made, so that each cell may be fitted for its 

 new destiny, as gelatine transformed to bone receives lime, 

 etc., into its cell structure, and so a pliant cell becomes 

 hard and resisting; but, moreover, cell differentiation, to 

 adapt itself to cell architecture, undergoes every form of 

 transformation which mechanism can devise to adapt itself 

 to the circumstances required, so that out of the same 

 primary impregnated ovum, in plants are formed pith, 

 spiral fibre, woody fibre, parenchyma of fruit, and the hard 

 structure of shell, as in the stone fruit, etc., etc. 



In animals we have, from the same primary impregnated 

 ovum, in the onward course of cell differentiation, serous and 

 mucous membrance, brain and nerve structure generally, 

 muscles, bone, integument, nails, hoofs, horns, and hair, 

 etc.* 



As cell differentiation and morphology in the vegetable 

 kingdom have received such marvellous elucidation through 

 Goethe, by a series of careful comparisons, and subsequently 

 from the patient researches of mam- microscopists and 

 physiologists, of whom Schleiden may be said to take the 

 lead, little more can be said than has already been said 

 upon this interesting subject in its leading outlines, though 

 in detail there is a large and ever increasing field of labour, 

 unoccupied in various special branches, of intense interest. 



But for the animal kingdom there has scarcely been any 

 attempt to unravel this interesting but marvellous subject, 

 and were it not for the probability of being able to condense, in 

 a very brief manner, some general observations, which appear 

 to have a very close relationship to the subject of morphology, 



* In connection with cell differentiation, read the able article upon 

 the " Structure and Growth of the Elementary Parts of Living Beings," 

 by Dr. L. Beale, British and Foreign Quarterly Review for July, 1862. 



