Pjirt \^TTT ^ e P s y c ^ ca ^Social Individuality 



Chapter I 



The Physiological Basis of the Psychical- 

 Social Individuality 



IT is preeminently the phylogenetic development of a certain organ 

 complex, the nervous system, that made possible the phylogenetic de- 

 velopment of individuality in the psychical-social sense. An individuality 

 similar to that of the higher mammals, and in particular of man, does not yet 

 exist in the more primitive organisms. In some of the earliest forms of animal 

 life there may be found instead of single individuals, groups of individuals, 

 colonies, which later may separate into single organisms. Gradually within 

 single organisms a differentiation of the component parts occurs and these 

 differentiated parts become more and more integrated and coordinated in 

 such a way that a complex whole results. The process of coordination takes 

 place largely through the nervous system in conjunction with the hormones, but 

 it seems that the nervous system itself may exert at least many of its functions 

 by means of specific hormone-like substances, which it transmits along the 

 nerve paths. As a rule, however, the hormones are carried to distant areas 

 by way of the lymph and blood channels and help to influence and correlate 

 the various parts of the organism. In this process of coordination there are 

 involved reflexes in which nerve fibers, ganglia cells and hormones, which 

 circulate in the bodyfluids, may cooperate. In a wider sense, we may include 

 among the hormones also certain contact substances, which are given off by 

 one tissue and which act on an adjoining tissue. 



Corresponding to the increasing integration of the individual, the nervous 

 system becomes more complex. This system is lacking in protozoa and in 

 sponges; however, in certain ciliate protozoans fibers exist, to which the 

 function of conduction of stimuli and coordination of movements have been 

 attributed. Sponges may be cut into many small particles and when these are 

 joined together at random they form a whole new organism. The definite 

 beginnings of a nervous apparatus consist in a system of nerves without a 

 central set of ganglia. The primitive nervous system of the simplest inverte- 

 brates is not yet polarized. The simplest type of a central nervous system is 

 found in the echinoderms ; in the starfish, for instance, there is a circumoral 

 nerve ring consisting of nerve fibers with attached scattered ganglia cells, but 

 as yet without real ganglia. This nerve ring functions as an organ which co- 



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