Identity of Structure of Plants and Animals. 239 



imprisoned within every oak. She is jealous of letting us 

 know this, and among the higher and more conspicuous forms 

 of plants, reveals it only by such obscure manifestations as 

 the shrinking of the Sensitive Plant, the sudden clasp of the 

 Dioncea, or, still more slightly, by the phenomena of the Cy- 

 closis. But among the immense variety of creatures which 

 belong to the invisible world, she allows more liberty to her 

 Dryads ; and the Protococci, the Volvox, and indeed all the 

 Algae, are, during one period of their existence, as active as 

 animals of a like grade in the scale. True, they are doomed 

 eventually to shut themselves up within their wooden cages 

 and remain quiescent, but in this respect they are no worse 

 off than the polype, or the oyster even. 1 ' 



In conclusion, the lecturer stated his opinion that the cell- 

 theory of Schwann consists of two portions of very unequal 

 value, the one anatomical, the other physiological. So far 

 as it was based upon an ultimate analysis of living beings, 

 and was an exhaustive expression of their anatomy, so far 

 will it take its place among the great advances in science. 

 But its value is purely anatomical, and the attempts which 

 have been made by its author, and by others, to base upon it 

 some explanation of the physiological phenomena of living 

 beings by the assumption of cell-force, metabolic-force, &c. 

 &c, cannot be said to be much more philosophical than the 

 old notions of " the actions of the vessels," of which physio- 

 logists have lately taken so much pains to rid themselves. 



" The living body has often, and justly, been called, ' the 

 house we live in.' Suppose that one, ignorant of the mode 

 in which a house is built, were to pull it to pieces, and find 

 it to be composed of bricks and mortar, — would it be very 

 philosophical on his part to suppose that the house was built 

 by brick-force ? But this is just what has been done with 

 the human body ; we have broken it up into ' cells,' and now 

 we account for its genesis by cell-force." 



