528 GENERAL ANATOMY. 



Bayle compares to an anticipated death, they cause pains more 

 or less sharp, and sometimes none ; they irritate and inflame 

 the neighbouring parts; they exercise a deleterious action 

 upon the organization, and particularly upon nutrition, even 

 upon that of the bones ; they extend and multiply then more 

 or less rapidly in the organization. 



The origin and cause of these tissues are unknown. They 

 have been regarded as innate or hereditary; as resulting from 

 an aberration of the formative action ; as organized beings de- 

 veloping and dying prematurely in the midst of the organiza- 

 tion ; as products, results of inflammation and irritation, &c. 

 These are so many hypotheses more or less ingenious and 

 more or less well founded. 



These tissues exist under the form of isolated masses, of en- 

 veloped masses, of infiltrations in the tissue of organs, &c. 



Sometimes they exist separately, sometimes combined with 

 each other and with other accidental productions, and with al- 

 tered tissues and humours. 



I. OF TUBERCLES. 



837. The tubercle, or tubercles, for they exist almosjt al- 

 ways in great numbers, constitute the most common morbid 

 tissue. They are called also scrofulous tubercles, because 

 they are met with in most cases of scrofula. 



This tissue exists under the form of isolated or enveloped 

 masses, and under that of infiltration. 



It commences by the gelatiniform state; but this state is 

 perceivable only when the tuberculous substance is infiltrated. 



It afterwards enters into the grayish, transparent, as if demi- 

 cartilaginous state: this is the first distinct period of isolated 

 tubercles; they constitute the miliary granulations of Bayle. 



These grains in enlarging, often unite in a mass; th'ey be- 

 come opaque, yellowish, friable, commencing by the centre. 

 The same change of colour ana* consistence takes place in the 

 state of infiltration ; it is y.et the state of crudity. 



They afterwards soften and liquefy: at this period, or even 

 in the preceding periods, there is produced much new tuber- 

 culous substance, e'ither4n mass, or by infiltration. 



