22 



GENERAL PHYSIOLOGY. 



Diagram of the organism.* 



cortical or epithelial globules (A A A), of which some ab- 

 sorb, others excrete, and finally others are impermeable or 

 neutral. In the interior, towards the middle far from the 

 surface (Fig. 6, B), are found a group of globules, relatively 

 permanent; viz., the nerve globules, which by means of their 

 prolongations are in communication with the peripheral 

 globules so as to be excited by one set and to react 

 upon another (reflex actions). Thus the blood globules 

 travel from the periphery towards the 

 centre, and vice versa (Fig. 6, C C) ; 

 and this circular current draws tow- 

 ards the centre the elements of nu- 

 trition absorbed by certain globules' 

 from the surface, and draws the de- 

 cayed portions of the globules at the 

 centre towards the globules upon the 

 surface, which are then thrown off(ex- 

 cremental secretions). The blood glob- 

 ule thus acts as a medium of exchange, 

 the same process in lower animals being effected by imbibi- 

 tion. 



Though these are the more simple forms of globular activ- 

 ity, yet it must not be forgotten, that these phenomena are 

 also linked with those belonging to chemistry and physics, 

 which likewise should be studied at the same time ; as for 

 instance the blood globule seems to be of service to the 

 nerve globule by establishing for purposes of nutrition a 

 communication between this deep-seated globule and those 

 at the surface ; but its circulation requires the intervention 

 of the nerve globule, which may excite the muscular fibre, 

 and thus give rise to certain mechanical phenomena of hydro- 

 statics, etc. 



Now it may be noticed that the collection of the phenomena 

 of animal life constitutes a living chain that must be artificially 

 broken for convenience of study. The most striking phenom- 

 ena is the wandering of the blood globule ; it might most 

 naturally seem that the commencement of our study should 

 be with this phenomenon ; but we prefer to commence first 

 with the nerve globule, which will lead us to study, secondly, 

 the non-globular forms (muscles) with which it is connected ; 

 and subsequently the movements and other mechanical and 



* A A A, Globules from the surface, epithelium. B, Central nerve-globules, 

 with prolongations coming from or going to the surface. C C, The circle of cir- 

 culation of the blood. 



