DEVELOPMENT OF LYMPHATICS. 95 



and that apparatus which suppUes the necessary pabuhim for their 

 growth, as well as for that of the muscles, nerves, glands, &c. 

 This "connective tissue" Kar 'e^ox^i', must detain us for vet a 

 moment while we consider how its corpuscles originate from em- 

 bryonic cells. The form assumed by these corpuscles depends 

 essentially on local conditions, upon the space available for their 

 evolution. The great majority become spindle-shaped, corres- 

 ponding to the elongated interstices left for their reception be- 

 tween the fibres of the connective tissue. Whenever the basis- 

 substance allows them to expand freely in all directions (as in 

 mucous tissue) they readily assume a stellate form, and anasto- 

 mose with one another by means of their processes. Should 

 they lie in the narrow fissures between fibrous bundles and 

 lamellae of larger size, they become flattened, forming epithelioid 

 plates, or else they may continue, even in this flattened condition, 

 to give off anastomosing processes, as in the cornea and tunica 

 intima of the arteries. Thereupon a portion of the protoplasm 

 very commonly stiffens into a homogeneous, colourless, highly 

 refracting substance ; we get stellate figures, plates, and fibres, 

 which must be carefully distinguished from the plates and fil)res 

 of the intercellular substance ; the necessary criterion being 

 readily afforded by their chemical properties, inasmuch as they 

 do not, like the intercellular substance, swell up and disappear 

 on the addition of acetic acid. It sometimes happens (liga- 

 mentum pectinatuni) that the entire cell, together with its nucleus, 

 undergoes the metamorphosis in question. More commonly, 

 however, the nucleus remains unaltered, together with a residual 

 portion of granular protoplasm, occupying, as a rule, the centre 

 of the stiffened cell. This is how the stationanj corpuscles of 

 the connective tissue originate; and in this state they remain 

 during the whole life of the individual, unless they are roused to 

 renewed activity by pathological irritation. 



§ 75. We come now to the lymphatics and lymphatic 

 GLANDS. This is the third and last of the chief constituents of 

 the intermediate apparatus of nutrition — the last in point of 

 time, not in point of importance. It is only when the rate of 

 embryonic development enters on a slower phase, after all the 

 other organs have been mapped out, and even developed to some 

 extent, that we can detect any lymphatics. Lymphatic glands 

 are still later in making their appearance. This is undoubtedly 



