338 THE BODY AT WORK 



external objects. Morphologically it is a median growth. 

 The adverb is one of those qualifying terms, convenient in 

 science, which direct thought without confining it. As used 

 above, it implies that anyone who passes before his mind the 

 cerebella of all animals from fishes to Man, and in all stages 

 of growth, from their earliest appearance in the embryo to 

 their condition in the adult, sees the organ as a median promi- 

 nence surmounting the medulla oblongata. The bulgings of its 

 sides which, in human anatomy, are termed hemispheres, 

 do not disturb its central, unpaired plan of structure. It has, 

 it is true, a lateral appendage on either side (the combined 

 flocculus and paraflocculus of mammalian anatomy), but this 

 lobe, although of great historic interest, is so small, as com- 

 pared with the median growth, as not to affect our general 

 conception of the form of the organ. By transverse fissures 

 the cerebellum is divided into a series of lobes. 



In appearance the cerebellum varies greatly in the different 

 classes and orders of Vertebrata. Yet underlying this variety 

 there is marked unity of plan. A sagittal section of the organ 

 of a shark, of a bird, of a kangaroo, of a dog, of a whale, of Man, 

 shows that it is divided, from before backwards, into the same 

 number of lobes in animals occupying every position from 

 the bottom to the top of the vertebrate scale. A very little 

 effort to grasp the significance of this mystic number, nine, 

 convinces one of the hopelessness of any attempt to correlate 

 the form of the cerebellum with the muscular development or 

 sensory endowments of vertebrates as a sub-kingdom. It is the 

 same for animals with limbs and animals without ; animals 

 with well-developed noses or eyes, and animals destitute of 

 one or other of these sense-organs. This uniformity is ex- 

 tremely significant, when contrasted with the wide differences 

 exhibited by the cerebral hemispheres. It shows that, unlike 

 the great brain which mediates between the several senses and 

 the muscular system, the little brain is concerned in bringing 

 about adjustments to the environment which are equally im- 

 portant to all animals, no matter how far they may depart 

 from the common type. The cerebellum is crossed by deep 

 fissures, dividing it into narrow convolutions or folia. The 

 folia are grouped in nine lobes. If the reader has secured as 

 an illustration the brain of a sheep, he will notice that the 



