CHAPTER XIX. 



Some General Considerations. 



It is well to avoid teleological explanations in Science. 

 It is, strictly speaking, incorrect to ask why, does an 

 animal possess a particular organ. One may however 

 call attention to homologies and analogies, and one may 

 describe the action of the organ. One may consider the 

 advantages or disadvantages to the individual or the 

 race, examine how the structure arises in the individual 

 and how it comes to be perpetuated in the race. One 

 may even speculate as to what amphimixial chance its 

 occurrence in the species was originally due. 



In other words, while taking care to avoid the 

 specious, gap-jumping half-truths and errors of tele- 

 ology, it is legitimate to indicate the anatomical, 

 functional, embryological and biological significance of 

 any structure. 



It is with the biological significance of the subepi- 

 thelial lymphatic glands that this section is concerned. 



The disadvantage of these glands in the body is their 

 proneness to more or less successful bacterial assaults. 

 Besides becoming the site of a local disease they may 

 become the portals of entry of general disease. Some- 

 times, while the glands do not succumb they are pro- 

 voked to such hyperplasia as to cause mechanical 

 disabilities such as nasal obstruction. 



The advantage of these glands is — so it is maintained 



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