TUMORS. 525 



have a very narrow but distinct muscular coat. The endothelial coat of the 

 capillaries is well developed; at some places the endothelia are clustered 

 together, with marks of division within the cluster, pointing to a proliferation 

 of the endothelial wall. Most of the capillaries are surrounded by a some- 

 what denser fibrous connective tissue, even in the myxomatous portion of the 

 tumor. This layer of fibrous tissue constitutes an adventitia of the capillary 

 blood-vessels more distinct than is ordinarily met with in normal tissues. 



The boundary-line between connective tissue and epithelium at many 

 places in the various specimens is sharply defined by a narrow zone of dense 

 fibers, identical with what has been termed the basement membrane ; at other 

 places, on the contrary, such a bounding zone is absent, and there is a gradual 

 transition of connective tissue into epithelium. In the latter cases the epi- 

 thelial bodies send offshoots into the reticular portion of the myxomatous tis- 

 sue, and it is impossible to tell where one terminates and the other begins. 

 Where a bounding layer of connective tissue exists, the columnar epithelia are 

 well defined ; where such a zone is absent they are ill defined, several rows 

 being sometimes piled up, each epithelium of a more or less fusiform shape 

 and very narrow. Surrounding each individual epithelial body, whether 

 spindle-shaped or well defined, and separating each from all the others, there 

 are very narrow light rims, pierced by extremely delicate threads. The main 

 mass of epithelium consists of cuboidal elements, which are polyhedral and 

 separated from each other by a light rim, the so-called cement-substance, 

 traversed by a large number of delicate threads or " thorns." Whenever the 

 razor has reached the surface of a cuboidal element in front section, the epi- 

 thelium looks as if studded with short hairs or thorns. The cuboidal epithelia 

 nearest the outer limit exhibit the cement-substance and the thorns less 

 markedly, and in the layer of flattened epithelium at the periphery, cement- 

 substance and thorns are scarcely recognizable. 



Most of the cuboidal epithelia hold in their interior a nucleus, the aspect 

 of which is, however, various. Not infrequently an epithelium has two nuclei, 

 of which one is finely, the other coarsely, granular, or both may be coarsely 

 granular, differing from each other only in size and in the number of granules 

 they contain. Occasionally a nucleus constitutes an almost homogeneous 

 shining mass ; and, again, a mass split up into two or three relatively large 

 lumps or clusters of granules. Around compact nuclei a broad light rim is 

 sometimes visible, evidently a vacuole i. e., a closed space filled with a 

 liquid. Large vacuoles in the centers of some epithelia are seen perfectly 

 empty, presumably because the nucleus that was in them has fallen out, or 

 been dragged out by the razor. 



Instead of the so-called thorns seen in cement-substance, frequently slender 

 spindles are wedged in between two epithelia of a higher refracting power 

 than the latter. Or a shining spindle-shaped corpuscle lies close against one 

 wall of an epithelial body, while the cement-substance at the opposite side of 

 the spindle is slightly distended, and pierced by thorns running at right 

 angles to the spindle. In other instances, the thorns between two epithelial 

 walls seem to have run together into an almost square or oblong homogeneous 

 shining rod ; the cement-substance, more or less broadened, surrounding the 

 rod on one or both sides and being pierced with other slender thorns. Again, 

 compact club-like or pear-shaped shining bodies, or a number of granules 

 in clusters of either a pear- or spindle-shape, are seen in the considerably dis- 

 tended cement-substance between two epithelia. These masses sometimes 



