CHAP. XI.] THE PSYCHOLOGY OF THE CAT. 375 



tiou. So also we have seen that the cat's circulating, respiratory, 

 and generative systems of parts, have each their special function, 

 in the performance of which their various constituent organs har- 

 moniously concur. (3) Thirdly, we have seen that each "organ" is 

 made up of a greater or less number of " tissues," which together 

 enable it to perform that function for which it is destined. Thus 

 the stomach consists of a basis of fibrous tissue, with much muscular 

 tissue, and is coated internally with epithelium, which, descending 

 into superficial depressions lines the various glands Avhich open upon 

 its surface. It is also richly supplied with vessels and nerves. Its 

 fibrous tissue maintains its shape and gives it the strength requisite 

 for its continued existence. Its muscular tissue is the source of its 

 motor power, without which it could not physically act, and its 

 epithelial lining, endowed vnth its secreting properties, is the source 

 of its digestive power, without which it could not act chemically on 

 the food contained within it. Its vascular structure afi'ords the 

 nutriment which its several parts need to repair the waste of its 

 continued action (which action, wthout this supply, would soon 

 come to an end), and its nervous tissue, with its property of "im- 

 pressionability," is the regulating agent which adjusts the actions of 

 the other tissues and of the entire viscus as one whole. (4) Fourth 

 and lastly, we have seen that each separate tissue is composed of its 

 own ultimate parts — different in each tissue, but which may, in all 

 cases, be said to consist of a matrix — fluid or solid, fibrous or homo- 

 geneous — with corpuscles, which are cells modified in one or another 

 mode. We have also seen that each tissue is at first cellular, and 

 is derived in one or another way from two layers of cells— epiblast 

 and hypoblast — themselves the product of the spontaneous divisions 

 of the germ-cell. Each of these cells, therefore, possesses, for a 

 longer or shorter time, its own activity and plays its own part in 

 contributing to the general property of that tissue of which it forms 

 a minute portion. Thus we have : 



(a.) Cell activities, contributing to that special vital property which 

 is characteristic of each tissue. 



{h.) Tissue activities, contributing to that special function which is 

 characteristic of each organ. 



(c.) Organ activities, contributing to that more complex function 

 which is characteristic of each system of organs, viewed ' as one 

 complex whole. 



(d.) Si/stem activities, consisting of the combined activities of sets, 

 or systems, of organs, and contributing to a higher and yet more 

 complex function. 



§ 7. For just as cell activities are subsumed by that of the tissue 

 they compose, and as the vital properties of tissues are synthesized 

 into a higher unity by the organ of which they form a part, and as 

 the functions of organs are embraced by the higher function of that 

 system of parts of which such organs are members, so are the func- 

 tions of all the systems of organs subsumed and synthesized into a 

 yet higher unity, which is the life of the animal itself, and which 



