278 ANNUAL 'KECORD OF SCIENCE AND INDUSTRY. 



changes from palingenesis to ccenogenesis he regards as 

 three, viz., acceleration, retardation, and heterotopy. 



It is clear that the two types of growth distinguislied by 

 Professor Haeckel are those which had been pointed out by 

 Professor Cope in the "Origin of Genera " as producing the 

 relations of "exact" and "inexact parallelism;" and that his 

 explanation of the origin of the latter relation by accelera- 

 tion or retardation is the same as that of the latter essay. 

 Proc. Acad, Nat. Science^ Philadelphia^ Feh.^ 1876. 



CEPIIALIZATION A FUNDAMENTAL PRINCIPLE IN THE DEVEL- 

 OPMENT OF ANIMALS. 



As an example of this principle among mammals, Professor 

 Dana says that the lowest forms are those having their loco- 

 motive functions located in the posterior parts of the body, 

 and that in the hio-her the forces or force-ors^ans are more 

 and more forward in the structure. For example, in the 

 whale the tail is the propelling organ, and is of enormous 

 power and magnitude, and the brain is very small, and is sit- 

 uated far from the head-extremity in a great mass of flesh 

 and bone, furnished with poor organs of sense; a grade up, in 

 the horse or ox, the tail or posterior extremity is no longer 

 an organ of locomotion, and is little more than a caudal whip- 

 lash, and locomotion is performed by organs situated more 

 anteriorly the legs ; and a well-formed head carries a brain 

 which is a vastly higher organ of intelligence tlian that of 

 the whale but the legs are simply organs of locomotion, and 

 the hinder are the more powerful ; and higher up, in the tiger 

 or cat, the fore-leo-s not the hind-leofs are the oi-ofans of 

 chief muscular force, and these have higher functions than 

 that of simple locomotion ; and, further, the body is propor- 

 tionately shortened, and the head is sliortened anteriorly, or 

 in the jaws, and approximates thus toward the condition in 

 man. The existence or not of a switch-like tail, as in ordi- 

 nary quadrupeds, has little bearing on the question of degi-ee 

 of cephalization, since the organ is not an organ of locomo- 

 tion, or one indicating a large posterior development of mus- 

 cular force. But, approaching man in the system of life, 

 even this seems to have significance. The principle of ceph- 

 alization is believed to be fundamental, " because, first, the 

 chief centre of nervous power or energy in an animal is at 



