218 MANUAL OF HISTOLOGY. 



In all this we see a resemblance between the structure in question 

 and gelatinous tissue. And, indeed, the greater part of this areolar tissue 

 existed at an earlier embryonic period in the form of a reticular mucoid 

 substance. The elastic fibres also are no less subject to variation, for we 

 meet both with fine and medium-sized specimens ; their amount, how- 

 ever, is but moderate. The connective-tissue cells proper are situated 

 either between the fasciculi in the form of fusiform or stellate elements, 

 or in the softer interstitial mass. Here also we encounter lymphoid 

 corpuscles, which may wander through the mucoid substance by virtue 

 of their vital contractility ; and yet we are unable to recognise any pre- 

 formed paths for them. 



According to its occurrence in more considerable amount in several 

 localities, this tissue has received corresponding names, such as sub- 

 cutaneous, submucous, and subserous areolar tissue. 



This, and indeed formless connective-tissue generally, is continuous at 

 its bounding portions through one of its bundles of fibres with some 

 structures made up of formed connective-tissue, e.g., the sheaths of nerves, 

 the fibres of fasciae, the subcutaneous and dense tissue of the cutis, &c. 



But this formless connective-tissue presents itself under other condi- 

 tions, namely, as the supporting or sustentacular substance of many organs 

 (Stutzmasse). Thus we meet with it in the larger glands. Here we 

 encounter either a fibrillated mass with fusiform or ramifying connective- 

 tissue cells, or the intercellular substance only appears streaky, while 

 the cellular elements may merely be evident as very much stunted 

 nuclear formations. Fibrillated tissue is to be found, for instance, in 

 the testicle and thyroid gland; streaky sustentacular substance in the 

 kidney (where we may isolate stellate cells from the medullary por- 

 tion in the young subject). The supporting tissue in the interior of 

 muscles and nerves frequently appears striped or streaky, but is at times 

 fibrillated. 



132. 



But the diversity of the so-called formed connective-tissue is far more 

 considerable, not only in respect to the manner in which its fasciculi and 

 elastic constituents are interlaced and interwoven, but also in regard to 

 its texture. And though, as a rule, we have to do with a well-marked 

 typically developed connective-tissue, yet there occur not unfrequently 

 very peculiar varieties. A few of these may here be mentioned. 



We have, first of all, certain connective-tissue structures, in which the 

 cells are exceedingly stunted, and seen as though only the nucleus had 

 been left over, and in which the intermediate substance is either homoge- 

 neous or streaky, but not fibrillated. Radiated corpuscles and elastic 

 fibres are absent, either totally, or only give very slight indications of their 

 presence. 



The tissue of the dental pulp apparently belongs to this class. And 

 yet we may have to do with a species of gelatinous or mucoid tissue here, 

 in that the interstitial matter does not become clear on the addition of 

 acetic acid. 



Again, the sheath or pcrineurium of the smaller nerves consists of a trans-- 

 parent substance, through which are scattered long oval and apparently naked 

 nuclei, measuring about O'0075-O'OIH mm. If we pass on from these 

 to somewhat more considerable branches, we find the ground-substance of 

 the envelope becoming stringy and fibrillated, while, instead of nuclei, we 



