1 8 MATTER. 



If it be desired to give a special position in the system of organisms to those 

 beings that occupy the lowest plane of development and that, representing to a cer- 

 tain degree the prototype in the family history, have as yet not been differentiated 

 into animal and vegetable, the so-called protists (Haeckel), these likewise would 

 occupy a distinct place in the foregoing arrangement by the side of animals and 

 plants. 



Morphology and physiology are coordinate branches of biology. A 

 knowledge of morphology is a prerequisite for the comprehension of 

 physiology, inasmuch as the functions of an organ can be correctly 

 understood only if its external form and its internal structure are pre- 

 viously known. The developmental history occupies an intermediate 

 position between morphology and physiology. It is a department of 

 morphology in so far as it has to do with a description of the parts of 

 the developing organism ; it is a physiologic study in so far as it investi- 

 gates the functions and vital phenomena during the period of develop- 

 ment of the organism. In all the branches of biologic science it is neces- 

 sary to enter upon a consideration of physical and cbemical principles. 



MATTER. 



The entire visible world, including all organisms, consists of matter, 

 that is, of the material or substance that occupies space. A distinction 

 is made between ponderable matter (in ordinary language often desig- 

 nated simply matter), which can be weighed upon the scales; and im- 

 ponderable matter, which cannot be weighed upon the scales. The latter 

 is designated ether (also luminiferous ether or light-ether). Ponderable 

 matter or bodies possess form (or shape), that is, the outline of their limit- 

 ing surfaces; also volume, that is, the amount of space they occupy; and 

 finally an aggregate condition, which takes a solid, liquid, or gaseous form. 



The ether fills the space of the universe, at any rate, with certainty 

 to the most remote visible stars. This light-ether, notwithstanding its 

 imponderability, possesses quite definite mechanical properties. It is 

 infinitely more attenuated than any other known form of gas, and never- 

 theless its behavior corresponds rather with that of a solid body than with 

 that of a gas. It more nearly resembles a gelatinous mass than air. 

 It takes part in the vibrations of the atoms of the most distant stars 

 associated with the luminous phenomena of the latter, and it is thus the 

 carrier of light, which through its vibrations it conducts to the visual 

 apparatus with inconceivable rapidity (300,000 kilometers in the 

 second). 



Imponderable matter (ether) and ponderable matter (substance) are 

 not sharply delimited from each other; on the contrary, the ether pene- 

 trates the interstices present in the smallest particles of ponderable 

 matter. 



If ponderable matter be conceived to be divided into gradually 

 smaller and smaller parts, in the process of progressive subdivision parts 

 would eventually be reached whose aggregate condition would still be 

 recognizable. These are designated particles. Particles of iron would 

 still be recognized as solid, those of water as fluid, and those of oxygen 

 as gaseous. If it be conceived that the process of division of the parti- 

 cles be carried to a further degree, a point will finally be reached beyond 

 which further division cannot be effected either by mechanical or by 

 physical means. In this way the molecule is obtained. A molecule, 



