DEGRADATION OF ORGANISATION 73 



It is then the mammals that must occupy the first rank in the animal 

 kingdom by virtue of their perfection of or<:;anisation and greatest 

 number of faculties [Recherches sur les corps vivants, p. 15). After 

 the mammals we no longer find a definitely viviparous reproduction, 

 nor lungs limited by a diaphragm to the chest and receiving all the 

 blood which has to be driven to the rest of the body, etc., etc. 



Among the mammals themselves it is in truth not easy to distinguish 

 what is really due to degradation from what is the effect of environ- 

 ment, manner of life and long-established habits. 



Nevertheless, traces of the general degradation of organisation 

 may be found even among them ; for those whose limbs are 

 adapted for grasping objects have a higher perfection than those whose 

 Umbs are adapted only for walking. It is among the former that 

 man is placed in respect of his organisation. Now it is clear that since 

 the organisation of man is the most perfect, it should be regarded 

 as the standard for judging of the perfection or degradation of the 

 other animal organisations. 



Thus the three divisions, into which the class of mammals is unequally 

 broken up, exhibit among themselves, as we shall see, a conspicuous 

 degradation in the organisation of the animals they contain. 



First division : nnguiculate mammals ; they have four limbs, flat 

 or pointed claws at the end of their digits but not investing them. 

 These limbs are in general adapted for grasping objects or at least 

 for hooking on to them. It is among these that the animals with 

 the most perfect organisation are found. 



Second division : ungulate mammals ; they have four limbs and 

 the extremity of their digits is completely invested by a rounded 

 horn called a hoof. Their feet serve no other purpose than that of 

 walking or running on the ground, and cannot be employed either 

 for cUmbing trees, or for grasping any object or prey, or for attack- 

 ing and rending other animals. They feed exclusively on vegetable 

 substances. 



Third division : exungulafe mammals ; they have only two limbs 

 and these limbs are very short, flat and shaped like fins. Their digits 

 are invested by skin and have no claws or horn. Their organisation 

 is the least perfect of all mammals. They have no pelvis, nor hind 

 feet ; they swallow without previous mastication ; finally they 

 habitually live in the water ; but they come to the surface to breathe 

 air. They have received the name of cetaceans. 



Although the amphibians also live in the water, coming out of it 

 occasionally to crawl upon the shore, they really belong to the first 

 division in the natural order, and not to that which comprises the 

 cetaceans. 



