Chapter I J 



The Effects of Various Extraneous Factors on the 

 Activity of the Organismal Differentials 



The reactions of hosts against transplants possessing individuality 

 differentials which show various and graded degrees of similarity 

 or difference from those of the hosts, have been described; also 

 the differences in the reactions noted in different kinds of tissues, these dif- 

 ferences depending upon an interaction between tissue differentials and in- 

 dividuality differentials. Furthermore the differences in the action of hosts 

 belonging to different species have also been analyzed and we have seen 

 that such species differences may affect the reactions which take place in the 

 host against strange individuality differentials. In the course of these discus- 

 sions, various problems of wider biological significance have been intro- 

 duced and these will now receive further consideration. 



(I) The interaction between tissues possessing different individuality dif- 

 ferentials, and the interaction between tissues possessing the same individuality 

 differentials but different tissue differentials. We have seen that organisms 

 react against strange individuality differentials by means of their bodyfluids 

 as well as of certain cells and tissues, or the latter may be the predominant 

 reacting agents. The reaction of the bodyfluids is the more specific one of 

 these two types. The tissue reactions as such are not entirely specific, but 

 they may become so if we take into account also the quantitative factors in 

 their activity, in particular the intensity and time of their action, and also the 

 interaction between different types of tissues and cells involved. The con- 

 nective tissue in general reacts very readily against various kinds of changes 

 in its environment. It reacts wherever cells and tissues in the neighboring 

 area are injured or killed; also against dead foreign bodies and it is influenced 

 in its behavior by variations in the activity of neighboring epithelial structures ; 

 but in addition, connective tissue reacts very finely to differences in the 

 individuality differentials in the adjoining tissues, discerning here the slight- 

 est differences and responding in accordance with a definite time curve. With 

 advancing age the connective tissue stroma undergoes changes similar to 

 those induced by strange individuality differentials. The lymphocytes too re- 

 act primarily in a non-specific manner against foreign bodies and against 

 injured tissues, provided these changes do not exceed a certain intensity. 

 It is the polymorphonuclear leucocytes which are activated whenever acute 

 changes of a relatively great intensity occur ; these cells become prominent as 

 soon as the difference between organismal differentials has attained such a 

 degree that the tissues are markedly injured, as, for instance, when tissues 

 possessing different species differentials adjoin each other, or when species 



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