TUMOES. 551 



The reticulum within the alveoli was either irregular or, in certain places, 

 arranged in a star-like manner. In the center was a cluster of plastids, send- 

 ing out filamentous processes which blended with the wall of the alveolus. 

 The spaces between the radiating threads were filled with a finely gran- 

 ular or homogeneous substance. In some alveoli, the reticulum presented an 

 appearance identical with that of myxomatous tissue. In addition to these 

 clusters of pale brownish-yellow epithelia, single, swelled, and dropsical-look- 

 ing ones were also present, with pale granular contents. The latter evidently 

 passed directly into the stage of myxomatous basis-substance. (See Fig. 

 229.) 



Colloid cancer, consequently, is by no means a distinct species of cancer, 

 but merely the result of secondary changes taking place in an originally 

 medullary cancer. In the manner as cancer elements arise from medullary 

 elements may fully formed epithelia, under certain unknown conditions, 

 retrogress to medullary elements. Whenever this occurs, medullary corpus- 

 cles are transformed into a reticulum containing a jelly-like, homogeneous 

 basis-substance, with interspersed remnants of epithelia. In the same man- 

 ner, fully developed connective tissue may break down into medullary tissue, 



I 



FIG. 228. COLLOID CANCER OF THE STOMACH. 



F, connective-tissue frame ; E, epithelia of cancer in the meshes of the connective 

 tissue; M, medullary corpuscles sprung from epithelia; &, medullary corpuscles changing 

 to colloid substance ; 2, alveolus filled with a homogeneous colloid substance, a few epithelia 

 left unchanged. Magnified 500 diameters. 



from which epithelia are developed, and epithelia may return to the medullary 

 stage from which connective tissue is developed. 



With these observations in the mind, the formation of the so-called ade- 

 noid cancer, too, can be readily understood. Here the alveoli originally con- 

 tained cancer epithelia. These were changed into medullary corpuscles, from 

 which were developed both the star-shaped myxomatous reticulum and the 

 basis-substance filling its meshes. The center is occupied by either an 

 unchanged epithelium or a cluster of medullary corpuscles, which have arisen 

 therefrom. 



Furthermore, we can understand the development of cystic cancer, the 

 smaller cavities of which are also very often traversed by a myxomatous 

 reticulum. The degenerative change of epithelia. into myxomatous basis-sub- 

 stance reaches here its highest degree, and leads to the complete destruction 

 of the myxomatous reticulum and to the liquefaction of its basis-substance. 



