154 GEOLOGICAL BIOLOGY. 



we have seen, the species, so far as superficial and even very 

 careful observation goes to-day, when expressed by so acute 

 an observer as Huxley, is fundamentally a group of like indi- 

 viduals, alike for space, alike for time duration. " A species 

 in the strictly morphological sense, is simply an assemblage 

 of individuals which agree with one another, and differ from 

 the rest of the living world, in the sum of their morphologi- 

 cal characters." * 



A Mutable Species necessarily Temporary. The idea of 

 " mutability," which was added to the conception of the 

 reality of species by the modern school of naturalists, is 

 intimately associated with the idea that the morphological 

 form of organisms, which constitutes their specific characters, 

 is temporary, and thus is distinguished from the characters of 

 atoms which are conceived of as continuing the same through- 

 out all time. The theory that the species is immutable was 

 associated with the conception of a primary principle under- 

 lying each form which was supposed to exist from the begin- 

 ning with persistent integrity. 



The Question of Mutability of Species entirely Distinct from 

 that of the Origin of Species. This discussion of species is also 

 a thoroughly legitimate process for the scientific investigator, 

 and the two views alike call for an explanation of their origin. 

 The Lamarckian school was not less free from the unscientific 

 cutting short of investigation by referring this origin to an 

 unknown cause. Cuvier and his school argued, We know the 

 species, but the first cause is a sufficient cause of its origin ; 

 here it is, and we do not know how it came to be. Lamarck 

 alike believed in scientific ignorance as to its origin when he 

 followed Aristotle in calling in spontaneous generation as the 

 explanation of its existence. According to Lamarck, Life 

 is purely a physical phenomenon. All the phenomena of life 

 depend on mechanical, physical, and chemical causes, which 

 are inherent in the nature of matter itself. The simplest 

 animals, and the simplest plants, which stand at the lowest 

 point in the scale of organization have originated, and do 

 originate, by spontaneous generation. In the first beginning 



* T. H. Huxley, "The Crayfish," etc., p. 29. 



