PRODUCTS, ADVENTITIOUS. 



143 



in, or close to the mouth) without coexistent 

 hairs. Nails and true cutaneous texture are 

 frequently present also. As transition-stages 

 to the purely adventitious formation of teeth 

 appear : the growth of supernumerary teeth 

 in the jaws ; of such teeth not in the jaws, 

 but still in the cavity of the mouth ; of such 

 teeth in the neighbourhood of the mouth, as 

 in the orbit.* Appearing in the mediasti- 

 num -f-, close to the diaphragm J, in the sto- 

 mach $, in the testicle, &c., they are purely 

 adventitious. The ovarian cyst is their chosen 

 seat, however, and their number may be very 

 considerable. In an ovarian cyst now before 

 us (Univ. Coll. Mus.), there are three sepa- 

 rate sets of teeth ; in the one are 2 molars, 

 2 bicuspidati, and 2 canines ; in the second, 

 2 molars, and 1 incisor ; in the third, 6 molars, 

 2 bicuspidati, 2 canine, and 1 incisor, 20 in 

 all. A case has been recorded by Ploucquet 

 and Autenrieth of a young sterile woman, in 

 whom an ovarian cyst contained 300 teeth, 

 a fact showing that the relationship (con- 

 tended for by Meckel and others) between the 

 combined number and character of adven- 

 titious and natural teeth is imaginary. 



The full consideration of the mode of de- 

 velopment and production of adventitious 

 teeth and hair would carry us into the regions 

 of Teratology ; and it must be confessed that 

 the most diligent investigators have failed to 

 find explanations for all cases. If it be true 

 that in some instances these products are the 

 residual parts of a regularly-formed foetus, in 

 others evidences of an attempt to produce a 

 fetus (in either of which cases they may be 

 the proceeds either of extra-uterine pregnancy 

 or of the formation of a monster by inclusion), 

 it is also certain, that in other instances all 

 explanations hitherto tendered have failed of 

 their mark. 



Cutaneous. Except in such cysts as those 

 just referred to, skin is never formed adven- 

 titiously. Losses of this texture are repaired 

 by a substance partaking of the characters of 

 induration-matter and of fibrous tissue. 



Mucous. Portions of mucous membrane 

 destroyed by ulceration are replaced by indu- 

 ration-matter, covered on the free surface 

 with a coating of epithelium, smooth and 

 glistening ; the border is, or is not, puckered 

 and finely nodulated. The attempts made by 

 Sebastian, Dr. Parkes j|, and others, to show 

 that the reparative power goes the length of 

 forming new intestinal mucous texture, the 

 precise anatomical counterpart of the old, 

 appear to us to have failed ; nor is there any 

 evidence that the cicatrix (either of the flat or 

 puckered variety) can even rudely discharge 

 the office of the texture it replaces. 



The pyogenic membrane of chronic ab- 

 scesses, tuberculous cavities and fistulas, has 

 many of the more obvious characteristics of 



1825. 



Barnes, Med. Chir. Trans, vol. iv. p. 316. 

 Gordon, Med. Chir. Trans, vol. xiii. p. 12. 



Berlin, Sammlung, t. iii. p. 264. 



Ruysch, Hist. Anat. Med. dec. in. No. i. p. 2. 



On the Dysentery and Hepatitis of India. 



mucous membrane. Of velvety look and 

 feel ; varying (like its prototype) in colour 

 from red to grey, slaty, or even black ; thick 

 as the inner coat of the stomach, or thin as 

 the lining of the frontal sinuses ; more or less 

 closely adherent to a stratum of induration- 

 matter (representing the submucous cellular 

 membrane of health), and covered with epi- 

 thelium ; capable of producing fungous vege- 

 tation from its surface ; and utterly inapt to 

 contract adhesions with itself; this struc- 

 ture has evidently many claims to the title of 

 pseudo-mucous. Its deficiency in villi and 

 follicles simply proves that it imitates the 

 least highly elaborated of nature's types. The 

 microscopical characters of this formation, 

 however, require full examination. 



Glandular. Destroyed glandular texture 

 is not reproduced ; much less does a de novo 

 development of such texture lie within the 

 range of morbid action. \ 



Muscle. There is no evidence that striped 

 muscular fibre is produced for purposes of 

 reparation, much less as a wholly adventitious 

 formation. 



Unstriped fibres occurring in the ureter, 

 walls of the gall bladder, and other excretory 

 organs, are rather hypertrophous, than adven- 

 titious, products, inasmuch as they naturally 

 exist in minute quantity in those organs. Of 

 the truly adventitious production of this fibre 

 nothing is satisfactorily known. 



SUB-CLASS II. 

 GERM-FORMATIONS OR PARASITES. 



Products, whose continued existence does 

 not depend upon direct access of nutrient fluid 

 from the organism they inhabit ; which spring 

 from a germ*, and simply live in, without 

 forming part of, the individual they infest, are 

 true Parasites. They do not in themselves 

 constitute disease, but always indicate its 

 presence, and sometimes entail its develop- 

 ment ; in the latter case they may be made 

 to propagate similar disease from organism to 

 organism. In some rare instances the organic 

 kingdom to which they belong is doubtful ; 

 the great majority easily take their places 

 among animals or vegetables. 



ORDER I. ANIMAL PARASITES. 



See ENTOZOA (vol. ii.). 



ORDER II. VEGETABLE PARASITES. 



Vegetable parasites form on the skin, on 

 mucous membrane, on new surfaces, upon or 

 within the body, and in certain of the fluids. 

 They indicate the existence (on the surface, or 

 in the fluid, affording them a habitation) of the 

 presence of chemical decomposition, and also 

 of the presence of some new material (albumi- 

 nous, saccharine, &c.), the result of diseased 

 action. Their precise influence and patho- 

 logical power in the human subject are yet 



* We set aside the notion of equivocal generation, 

 inasmuch as observation, so far as it goes, deposes to 

 the necessity (at least the existing necessity) of pro- 

 pagation from germs. 



