192 CONNECTIVE TISSUE. 



ing greatly in different animals. Sometimes they run parallel 

 with each other, sometimes they interlace in different directions. 

 They are coarser in the middle portions of the tissue, and gradu- 

 ally grow thinner as they approach the periphery; here they 

 often blend with the adjacent fibrous connective tissue of the 

 perichondrium. Not infrequently we see at the points of inter- 

 section of the elastic reticulum slender oblong nuclei, which is a 

 positive proof that the elastic fibers have originated from branch- 

 ing plastids found between the territories of the cartilage 

 corpuscles. 



The meshes of the elastic reticulum contain a chondrogenous 

 basis-substance, and usually in the middle of each mesh one or 

 two cartilage corpuscles can be distinguished. In young individ- 

 uals these corpuscles are either homogeneous and shining, or 

 composed of coarse, bright granules and destitute of nuclei. 

 They are more bulky in the middle of the plate of the reticular 

 cartilage, and become flattened toward the perichondrium, where 

 they undergo a gradual but rapid change into the spindle-shaped 

 corpuscles of the perichondrium. Some of the cartilage corpus- 

 cles are pear-shaped, and unite by means of slender, stem-like off- 

 shoots with the elastic reticulum. Their periphery is everywhere 

 thorny, which indicates that their structure, as well as that of 

 the chondrogenous and elastic basis-substance, is identical with 

 that of all other connective-tissue formations.* 



Little is known regarding the senile changes of this tissue. 

 It is asserted that in persons of middle and advanced age the 

 elastic cartilage of the auricle of the ear becomes fibrous, and H. 

 Miiller has observed calcification and ossification in auricles of 

 dogs. 



According to O. Hertwig, the first development of the elastic 

 fibers takes place in the shape of extremely delicate fibrillae, as 

 the result of the "formative activity of the cartilage cells" in 

 their most peripheral portions. The f urther growth, he says, is 

 the result of u intussusception," independently of the cartilage 

 corpuscles. I consider the development of reticular cartilage to 

 be the same as that of the reticular myxomatous tissue. Territo- 

 ries are formed by coalescence of embryonal plastids, in which 



* As a matter of curiosity, it is worth mentioning what method A. 

 Rollett (" Manual of Histology," by S. Strieker, American edition, 1872) 

 recommends for obtaining the best specimens of reticular cartilage. "Boil 

 the auricle of the ear of man for a short time, dry it, and finally make sec- 

 tions of these boiled mummies." 



