368 Dynamic Theory. 



organ in the proper condition to appropriate nourishment. Without 

 such activity, therefore, it degenerates, first in its quality or potentiality, 

 and second, in its size by loosing its degenerated tissue without acquir- 

 ing new material in its place. The degeneracy of one organ often causes 

 the disuse of some other with which it is related. If a motor nerve be 

 paralyzed, the muscle whose movement depends upon it will become 

 atrophied ; and conversely, if a muscle be disabled, as in case of hip-joint 

 disease, or amputation of a limb, not only the nervous connections with 

 the brain will become atrophied, but so much of the cerebrum itself as 

 relates to the part will shrivel up and become f unctionless. Atrophy of 

 the eye. involves the disuse of the optic nerve and certain brain centers 

 and their consequent atrophy, and vice-versa. When the muscles of a 

 limb are reduced through disease, the bones are involved also and be- 

 come lighter, as shown by experiments by Dr. J. Reid. (Carpenter.) 



Herbert Spencer raised the question , what sort of units form the im- 

 mediate constituent elements of the different tissues that go to make up 

 the body ? That is, what are the little crystalline bodies which, by their 

 polar structure, are fitted to be placed together to form a larger one ? 



First, he shows that these units cannot be atoms ( or molecules ) of 

 the complicated chemical compounds that enter into the composition of 

 organic bodies atoms of albumen, fibrine, gelatine, &c. , for in that 

 case there would be nothing to account for the unlikeness of different 

 organisms < ' since so many plants and animals are mainly built up of 

 such atoms. " For since the polarities of the atoms determine the forms 

 they compose, like units in all might be expected to develop all alike, 

 which they do not. He therefore rejects these chemical units, and he 

 likewise rejects' the "morphological unit" the name he gives the 

 "cell " as the unit sought. The cells it is true, compose tissues gen- 

 eralty, but still they are not universal. { < Finding that in many cases a 

 fibrous tissue arises out of a structureless blastema without cell forma- 

 ation ; and finding that there are creatures such as Rhizopods which are 

 not cellular, but nevertheless exhibit vital activities and perpetuate in 

 their progeny certain specific distinctions ; we are forbidden to ascribe to 

 cells this peculiar power of arrangement. Nor, indeed, were cells uni- 

 versal, would such an hypothesis be acceptable, since the formation of a 

 cell is, to some extent, a manifestation of this same peculiar power. 

 If then this organic polarity can be possessed, neither by the chemi- 

 cal units nor the morphological units, we must conceive it as possessed 

 by certain intermediate units which we may term physiological. There 

 seems no alternative but to suppose that the chemical units combine into 

 units immensely more complex than themselves, complex as they are ; 

 and that in each organism the physiological units produced by this 

 further compounding of highly compound atoms (molecules) have a 



