71(> 



THE AMEBIC AX NATURALIST 



[Vol. XLVII 



ively, of one or of two occipital condyles or joints 

 between skull and backbone. The two largest families 

 of living conifers, the Abietinese and the Araucarineae, 

 are roughly separable on several characters, but the only 

 distinction to which no exception has been found is the 

 presence or absence of "bars of Sanio," minute bands of 

 pectose on the walls of the wood elements. Similarly, the 

 monocotyledons and dicotyledons, the two great divisions 

 of the higher seed plants, are ultimately separable, as 

 their names imply, by the number of the cotyledons in 

 the embryo. It can not well be claimed that any of 

 these characters or many others which are common to 

 wide groups of animals and plants are in themselves 

 physiologically important but it is equally impossible to 

 distinguish others, of great value for survival, with which 

 these are correlated. 



Darwin frequently calls attention to the fact, now so 

 generally admitted, that a classification based on one or 

 a few distinctions is of much less value than one which 



Such a group of characters, however, corresponds to what 

 we have mentioned as the general plan or type of struc- 

 ture and consists, at least in the broader groups of organ- 

 isms, of features which are mainly unimportant for 

 survival. 



It is possible to maintain that the success or failure of 

 an organism depends more on some deeply seated prop- 

 erty of its protoplasmic make-up, such as its powers of 

 resistance or adaptability, than on any external and vis- 

 ible structures. But if there is a correlation of such 

 fundamental abilities with features of structure, is it not 



group, there are some individuals which are dominant and 

 successful and others which are unsuccessful and are 



characters of great functional impo 

 with those which are of no phvsiol 

 The fact that so often in the same f; 

 members possess the typical conserva 



