w n 



TISSUES IN GENERAL. 133 







which is by no means an individual, as each unit is in direct, 

 living connection with all neighboring units. 



Let us begin with the analysis of the units in the formations 

 termed " connective tissue." In the center of the element is the 

 nucleolus, around this the nucleus, and next a protoplasmic body, 

 hitherto termed " cell" j this is surrounded by a protoplasmic mass, 

 infiltrated with a glue-yielding basis-substance, and within this 

 unit of the tissue the living matter is uninterruptedly connected. 

 It is accumulated in the center in the shape of a compact nucleolus; 

 next it constitutes a sometimes narrow, sometimes wide, reticu- 

 lum, and incloses this reticulum as a continuous layer in the 

 shape of the nucleus; then it forms a somewhat wider reticulum, 

 holding protoplasmic liquid, and, as a rule again, a continuous 

 shell, inclosing this reticulum in the shape of the cell; and, lastly, 

 is spread out in the shape of a relatively wide reticulum, whose 

 meshes are infiltrated with basis-substance, as the cell-territory. 

 (See Fig. 46.) 



This schema may exhibit modifications if either the nucleus in 

 toto or the whole element in toto is a compact, homogeneous mass 

 of living matter. Such conditions are due, as I have explained 

 before (see page 46), to differences of age of the protoplasm. 



Each of the constituents of a unit described is separated from 

 the neighboring constituents by a space, as a rule, containing a 

 liquid, traversed not by a reticulum, but simple filaments of the 

 living matter. Such spaces, therefore, exist around the nucleolus, 

 around the nucleus, around the protoplasm, or cell, and around the 

 infiltrated portion of the unit, although until the present time 

 only the pericellular spaces were known. In all these spaces a 

 circulation of liquids can take place, and each may be filled by 

 parenchymatous injection with colored substances. Such injec- 

 tions have been made around the nucleus (by Mac-Gillavry) j 

 around the cell (by Kowalewsky and others) j around the bor- 

 ders of the units of the tissue, and, lastly, around the perivascu- 

 lar spaces. By such forcible injections the connecting filaments 

 are torn and the protoplasmic bodies become displaced and com- 

 pressed. We can readily understand how lymph-clefts, desti- 

 tute of walls, could be manufactured by such parenchymatous 

 injection. 



The schema of the units of epithelium is different. In 

 the center of the element is the nucleus with the nucleolus. 

 Both are imbedded in a protoplasmic body surrounded by the 

 shell of cement-substance common to all neighboring elements, 



