RELATIONS OF ANIMAL MORPHOLOGY 245 



logy, such as embryology in its broadest sense, the phenomena of 

 regeneration and regulation in organisms, 1 and especially the evo- 

 lutionary history of specific forms. While in taxonomy we must 

 continue to have botanists and zoologists, as we shall continue to 

 have ornithologists, entomologists, etc., yet outside of the purely 

 descriptive subsciences I would the gulf between botanists and zoo- 

 logists were annihilated, and that we had biologists separated rather 

 in regard to subjects, and university chairs, journals and societies 

 devoted to evolution, cytology, ontogenetic processes, and form 

 regulation, without regard to the systematic position of the material 

 studied. Then we might hope to advance a subject instead of mull- 

 ing over endless descriptive details. 



We have next to consider the relations of morphology to form 

 evolution, or phylogeny. Before we can consider how a new form 

 arises, we must clear the field by seeking some element of form. 

 The mass of material in the organic, like that in the inorganic 

 world, early led to an attempt at the classification of these materials 

 in both biology and chemistry. In chemistry a certain number of 

 kinds of materials have in course of time been catalogued and are 

 called substances, each of which has its particular molecular com- 

 position. In biology, likewise, many thousand kinds of organisms 

 have been catalogued, and these are called species, each made up 

 of particular sorts of individuals. Chemistry has gone a step farther 

 in its analysis of non-living matter, and recognized that the different 

 molecules are made up of diverse combinations of a relatively 

 small number of units called atoms. To-day biology has to recog- 

 nize that its individuals are likewise diverse combinations of units 

 relatively very numerous which, following De Vries, 2 we call 

 unit characters, or we may use the simpler name of "character- 

 istics." Characteristics are thus to individuals what atoms are to 

 molecules. As the qualities and behavior of molecules are deter- 

 mined by their constituent atoms, so the essence of the individ- 

 uals of any species is determined by its constituent characteristics. 

 And as we may construct new substances at will by making new 

 combinations of atoms, so we may produce new species at will by 

 making new combinations of cluracteristics. The making of new 

 combinations in molecules or species is a useful work, but it is not 

 evolution. Evolution in the non-organic or the organic world is first 

 achieved when we can make new atoms or new characteristics, 

 as the case may be. 



This conception of species, which has arisen during the present 



' See T. H. Morgan, Regeneration, New York, 1901. 



2 Compare De Vries : Die Mutationstheorie, ' ' Die Eigenschaften der Organismen 

 aus scharf von einander unterschiedenen Einheiten aufgebaut sind." Bd. I, p. 3, 

 Leipzig, 1901. 



