78 AMERICAN ASSOCIATION FOR THE ADVANCEMENT OP SCIENCE. 



I propose to present some thoughts on species from the latter point of view, 

 reasoning from central principles to the circumferential, and, if I mistake not, We 

 shall lind the light from this direction suiEciently clear to illumine a subject -which 

 is yet involved in doubts and difficulties. 



The questions before us at this time are— 



1. "What is a species ? 



2. Are species permanent 8 



3. What is the basis of variations in species? 



1. What is a species ? 



It is common to define a species as a. group comprising such individuals as are alike 

 ^in fundamental qualities; and then by way of elucidation, to explain what ia 

 meant by fundamental qualities. But the idea of a group is not essential ; and 

 moreover it tends to confuse the mind by bringing before it, in the outset, the end- 

 less diversities in individuals, and sugges'ing numberless questions that vary in 

 ansv^er for each kingdom, class or subordinate group. It is better to approach 

 the subject from a profounder point of view, search for the true idea of distinc- 

 tion among species, and then proceed onward to a consideration of the system of 

 variables. 



Let us look first to inorganic nature. From the study of the inorganic world, 

 ■we learn that each element is represented by a specific amount or law of force; 

 and we even set down in numbers the precise value of this force as regards one of 

 the deepest of its qualities, chemical attraction. Taking the lightest element as a 

 unit to measure others by, as to their weights in combination, oxygen stands in our 

 books as 8 ; and it is precisely of this numerical value in its compounds : each 

 molecule is an 8 in its chemical force or law, or some simple multiple of it. In 

 the same way there is a specific number at the basis of other qualities. Whenever 

 then the oxygen amount and kind of force was concentrated in a molecule, in the 

 act of creation, the species oxygen commenced to exist. And the making of 

 many such molecules instead of one, was only a repetition in each molecule, of the 

 idea of oxygen. 



■ In combination of the elements, as of oxygen and hydrogen, the resultant mole- 

 cule is still equivalent to a fixed amount, condition, or law, of chemical force ; and 

 this law, which we express in numbers, is at the basis of our notion of the new 

 species. 



It is not necessarily a different amount of force ; for it may be simply a differ- 

 ent state of concentration or different rate or law of action. This should be kept 

 in mind in connection with what follows. 



The essential idea of a species, thence deduced is this : a species corresponds to 

 a specific amount or condition of concentered force^ defined in the act or law of 

 creation. 



Turn now to the organic world. The individual is involved in the germ-cell 

 from which it proceeds. That cell possesses certain inherent qualities or powers, 

 bearing a definite relation to external nature, so that, when having its appropriate 

 nidus or surrounding conditions, it will grow and develope out each organ and 

 member to the completed result, and this, both as to all chemical changes, and the 

 evolution of the structure which belongs to it as a subordinate to some kingdom, 

 class, order, genus and species in nature. The germ-cell of an organic being de- 

 Telopes a specific result ; and like the molecule of oxTgen, it must correspond to 



