Page:Archives of dermatology, vol 6.djvu/390

378 C. HEITZMANN;

THE body of higher developed animals is made up of four kinds of tissues. These are connective tissue, muscles, nerves, and epithelium. The first three are formations of the middle embryonal layer (mesoblast), which produces the main bulk of the body. The last are formations of the upper and lower embryonal layers (epi- blast and hypoblast), which furnish the outer coat of the body — epithelium of the skin and its elongations, including the crystalline lens — and the coats of all cavities of the body, being in a direct or indirect communication with the outer surface, i.e., the epithelia of the respiratory, the digestive, and the urino-genital tracts. Amongst the formations of the three embryonal layers, only the connective tissue is supplied with blood- and lymph-vessels. No blood- or lymph-vessel enters muscle- or nerve-fibres or epithelium. Based upon these facts, we reach a simple and clear classification of morbid growths or tumors, — viz., new formations of tissues with- out typical termination (Liicke).

We distinguish four varieties of fully-developed connective tissue, — viz., myxomatous or mucoid, fibrous, cartilaginous or chondro- genous, and osseous. According to these varieties, we have four typical kinds of connective-tissue tumors, which are:

I, Myxoma; 2, Fibroma; 3, Chondroma; 4, Osteoma.

Additional formations of the connective tissue are fat and blood- vessels, and, further, formations of the mesoblast closely combined with connective tissue, — namely, muscles and nerves. These forma- tions again result in the production of four kinds of tumors, which are:

5, Ivipoma; 6, Angioma; 7, Myoma; 8, Neuroma.

I. Myxomatous or mucoid tumors appear in three varieties : a. A protoplasmic reticulum, with large nuclei at the points of inter- section, traversing a soft, jelly-like basis-substance, which latter is either homogeneous, or slightly granular, or slightly fibrous. The meshes of the basis-substance again hold single or multiple proto- plasmic bodies, apparently isolated. This variety is a full imitation of the structure of the umbilical cord, b. A delicate fibrous retic- ulum, with small nuclei at the points of intersection, traversing a soft, jelly-like, mostly homogeneous or granular basis-substance, the meshes of which hold single protoplasmic bodies or such bodies in small number. This variety is an imitation of the human embry- onal derma and mucous tissue in the third and fourth month of development. c. A fibrous reticulum, with relatively numerous blood-vessels, holding in its meshes solid, globular lumps of living

ation, Newport, R. I., August 31, 1880. For discussion see p. 434.
 * Read at the fourth annual meeting of the American Dermatological Associ-