THE SPIRAL TYPE OF CLEAVAGE. 265 



organism, and which, even when once modeled, may be 

 brought back, like a bit of clay, to the original condition and 

 remodeled into a different form if necessary. And further, 

 the material connection between cell and cell, which occurs so 

 widely, is of the utmost importance, for through this, as I 

 believe, the cell becomes simply a part of the organism, in 

 touch with the whole, influenced by the whole, and exercising 

 in its turn an influence upon the whole. Whether that pecul- 

 iar property of protoplasm which we know as organization be 

 merely the expression of its chemical and physical structure, 

 or, as Driesch believes ('99), the expression of a mysterious 

 force wholly different from any in the inorganic world, it is the 

 organism — the individual, which is the unit and not the cell. 



University of Chicago. 



LIST OF LITERATURE CITED. 



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Univ. Circ. Vol. xvii, No. 123. 

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f. Entwicklungsniechanik d. Organismen. Bd. vi. Heft 2. 

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Vol. ii. No. I. 

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and Sea-Urchin Eggs. Journ. of Morph. Vol. xii. No. 2. 

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cristata, etc. Zool. Bull. Vol. i. No. 2. 

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Vol. xiii. No. I. 

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at Woods Holl, Sessions of 1897 and 1898. 



