734 Fluctuations 



as innumerable, and thereby to explain the laws 

 of fluctuations, remains uncertain. Of course 

 the easiest way is to assume that they combine 

 in the same manner as the causes of chance, and 

 that this is the ground of the similarity of the 

 curves. On the other hand, it is manifestly of 

 the highest importance to inquire into the part 

 the several factors play in the determination 

 of the curves. It is not at all improbable that 

 some of them have a larger influence on indi- 

 vidual, and others on partial, fluctuations. If 

 this were the case, their importance with respect 

 to questions of heredity might be widely differ- 

 ent. In the present state of our knowledge the 

 fluctuation-curves do not contribute in any 

 large measure to an elucidation of the causes. 

 Where these are obvious, they are so without 

 statistics, exactly as they were, previous to 

 Quetelet 's discovery. 



In behalf of a large number of questions con- 

 cerning heredity and selection, it is very desir- 

 able to have a somewhat closer knowledge of 

 these curves. Therefore I shall try to point out 

 their more essential features, as far as this can 

 be done without mathematical calculations. 



At a first glance three points strike us, the 

 average or the summit of the curve, and the ex- 

 tremes. If the general shape is once denoted by 

 the results of observations or by the coeffi- 



