526 THE POPULAR SCIENCE MONTHLY. 



the case which varies very greatly with individuals, and even varies 

 with the nervous states of the same individual. And this suggests the 

 further thought that a careful comparison of individuals relatively to 

 their illusion-capacity might elicit some interesting and perhaps valu- 

 able facts concerning the relation between the states of brain-organiza- 

 tion and the sensations of the more highly specialized organs of sense. 

 Brain. 



4t 



EYOLUTIO^" OF THE CHEMICAL ELEMENTS.* 



By LESTEE F. WAED, A. M. 



MUCH may be said in favor of the hypothesis of the progressive 

 development of all the stable forms of matter by a true pro- 

 cess of evolution from antecedent states. Indeed, in the higher forms 

 of matter, in those which we know to be of composite constitution, 

 this process is more or less thoroughly understood. Most of the ob- 

 jects which surround us, whether organic or inorganic, are known to 

 consist of a great number of elementary parts of the same size and 

 form which are aggregated in definite ways to form the general 

 mass which each such object presents. These particles, which are 

 alike for all parts of the same object or species of object, are un- 

 like for different objects. Each object is an aggregate of elements of 

 the same species, and these elements are the units of aggregation. 

 All aggregates which have been thus far resolved into these units 

 have confirmed this law. What is known, however, of the higher 

 aggregates of matter is sufficient to establish another law, viz., that 

 such aggregates are the result of the successive recompounding of 

 units of aggregation of descending orders. The units of aggregation 

 of aggregates of the higher orders are compounds of lower units. 

 This is physically proved to be true of all aggregates of known com- 

 position. 



In biology we have the individuals of various orders, both animal 

 and vegetable, in which the lower forms are taken up bodily and made 

 to enter as integral units into the higher forms. Not only are all ani- 

 mals and plants compounded of innumerable cells as ultimate biologi- 

 cal units, but the earlier forms, which are aggregations of cells, are 

 repeated as units in the higher forms. The tape- worm is an animal of 

 the third order, the cell being taken as the first, but its segments are 

 so feebly integrated that they possess all the essential characteristics 

 of perfect animals. In the higher Annulosa, the integration is more 

 complete, but the composite character is still evident. In the Yerte- 

 hrata, the process of coordination has proceeded so far that only the 



* Read before the Philosophical Society of Washington. 



