80 ON VAKiEXIKS, RACES, SUli-Sl'KCltS, A.'^D SPECIES. 



the differences presented by the typical varieties of the species 

 Delta. 



4. When the positions in which the angles made by the axis 

 of the cylinder and the vertical are still larger, they correspond 

 to those modifications which are important enough to give dis- 

 tinct varieties, whether they be races or sub-species ; they San 

 consequently be applied to varieties of the species Beta^ to 

 varieties and races of the species Gamma and Delta, and to 

 sub-species of Epsilon* 



Another consequence may be drawn from the comparison 

 which we have just made. As soon as the disturbing force 

 ceases to act on the cylinder, it resumes its normal position ; and 

 in like manner as soon as tlie disturbing causes of modifica- 

 tion cease to act on living bodies, the modifications themselves 

 disappear, and the individuals presenting them tend to re-assume 

 the typical form of their respective species. But it must not be 

 forgotten that this is not unexceptionably true ; for there can, we 

 tliini^, be no doubt that individuals of certain species remain 

 modified, although removed from the causes and circumstances 

 which gave rise to the modifications ; and, moreover, as a general 

 rule, those modifications in living bodies which can be effaced, 

 do not disappear the moment the influences wliich caused them 

 have ceased to operate. 



We proceed to examine these two classes of contradictory 

 facts, and we shall first consider those wliich by tiieir evidence 

 and importance lead most to general conclusions. We shall 

 then give our attention to the special questions proposed for dis- 

 cussion at the beginning of the present paper relating to Count 

 Odart, in the \\o\>e that the details which will have preceded 

 tlieni will be justified by the light they will throw upon the 

 subject. 



Article L 



Stabilitij of Organic Forms. 



Our knowledge of the stability of organic forms is derived (A) 

 from a comparison of the individuals of different species of plants 

 and animals in actual existence, with extinct individuals of the 

 same species : (B) from observations on the permanence of one 

 and the same form, made either on the individuals of a series of 

 successive generations, or on individuals of different species of 



* As to the races and varieties of the sub-species Epsilon, they may be 

 represented by the preceding positions of the cylinder, if we suppose each 

 sub-species to correspond to the case in which the axis of the cylinder 

 deviates very little from the vertical ; or, in other words, if we suppose 

 varieties of sub-species to be varieties of a species. 



