142 



vessels; the second in the extravasation of 

 blood ; the third in the passage of this into 

 canals (manufactured, as it were, for its recep- 

 tion); the fourth in the formation of walls 

 round this blood : the difficulty in this 

 hypothesis lies in the alleged canal-formation. 



The notion that new vessels are independent 

 productions is supported: by the analogy of 

 the process in the vascular area of the chick ; 

 by the fact that the new cannot at first be 

 injected from the old vessels ; by the analo- 

 gical fact that new blood-particles appearing in 

 lymph in the frog are of spherical shape (as 

 in the foetal condition), and are therefore not 

 particles previously contained (for these are 

 oval) in the old vessels; by direct observation 

 both with the naked eye and with the micro- 

 scope. In truth in one spot of a new material 

 to be vascularized may be seen minute uncon- 

 nected points of blood ; at another, a number 

 of such points united in linear juxtaposition, 

 so as to form a streak of blood unenclosed in 

 any distinct vessel ; elsewhere a vascular in- 

 vestment is found for a similar streak ; further 

 on a like piece of delicate tube divides at each 

 extremity into a number of tapering ramifica- 

 tions, assuming a stellate arrangement, the 

 whole assimilable to the system of the portal 

 vein, and capable of effecting an independent 

 oscillation of the contained blood. What is 

 thus seen with the naked eye is corroborated 

 with the microscope ; but this instrument has 

 not yet made clear either the precise structural 

 characters or developmental process of the 

 new vessels : we simply know that these are 

 wider, and of thinner walls than natural capil- 

 laries. The manner in which communication 

 is effected between old and new vessels (when 

 the latter first become the seat of true circu- 

 lation) is unknown. That the formation of 

 new blood precedes that of new vessels seems 

 fully established ; just as the cell-structure, 

 destined to fill a loculus in a new growth, 

 forms before the loculus-walls that contain it. 



The production of new blood and vessels 

 signifies the appearance of various new chemi- 

 cal compounds in the vascularized material ; 

 the globulin formation may be understood, 

 that of the haematin is at present inexplicable, 

 unless we accept the extravasation-theory 

 above referred to, which supplies iron as 

 required. 



Further observations are wanting as to the 

 shortest possible time in which new vessels 

 may be formed ; we have seen them in peri- 

 tonaeal exudation aged seven days ; Everard 

 Home speaks of their appearance in twenty- 

 nine hours. They form in growths, indura- 

 tion-matter, hypertrophy of natural textures, 

 and pseudo-tissues. Generally produced on 

 a limited, they in rare instances form on an 

 extensive scale ; the most singular illustration 

 of the latter appears in the new system of ves- 

 sels generated in tuberculized lungs (Schroeder, 

 Guillot), which effects not only a complete 

 change in the anatomical condition, but in the 

 physiological actions, of those organs.* 



* Louis on Phthisis, ed. cit. p. 29. 



PRODUCTS, ADVENTITIOUS. 



Erectile Tissue. (See ANGEIECTOMA, p. 

 128.) 



Lymph Vessel. Schroeder van der Kolk 

 has described lymph vessels of new formation 

 in peritoneal pseudo-membrane ; it is gene- 

 rally admitted that his' observations require 

 corroboration, and we know of no other 

 evidence bearing on the question. 



Fibrous and Spongy Cartilage. Fibro-carti- 

 lage forms in some rare instances the material 

 by which imperfect union of bone is effected ; 

 its own losses are supplied by a similar ma- 

 terial ; it does not appear to form in an 

 absolutely adventitious manner. Nor does 

 spongy cartilage grow as a-new product, and 

 of the reparation of this texture little is known. 



Hair. The adventitious production of 

 hairs is not singularly rare, and though, no 

 doubt, much fantastic matter has been written 

 on their places of attachment, the following 

 localisations may be admitted as real. The 

 tongue*, the caruncula lachrymalis, the cor- 

 neaf, the internal surface of the gall-bladderf, 

 the nymphae, the vagina, (in connection with 

 fat) tumours of the uterus and of the fauces. 

 Cases of defecation of hair and of pilimiction 

 are for obvious reasons to be received with 

 distrust || ; but the rupture of an ovarian cyst 

 into the bladder may sometimes have caused 

 discharge of hair with the urine. 



Cysts of new formation are the favourite 

 site of adventitious hair ; pilous cysts have been 

 seen occupying the ovary, uterus, subcutaneous 

 membrane, muscular substance, walls of the 

 stomach, testicle, liver, thyroid gland, omen- 

 turn, and peritoneal cavity. The ovarian is 

 of all cysts the most frequent abode of these 

 productions. The hair is scattered through 

 the fatty matter generally present, or adherent 

 to the walls of the cyst, either by a bulb or by 

 simple embedding, or by means of cretaceous 

 particles. The colour of the hairs varies 

 greatly, sometimes even in the same, cyst ; 

 their length from a few lines to upwards of 

 two feet. They commonly resemble in struc- 

 ture the hairs of the head, rarely those of 

 the pubis : their possession of roots has been 

 denied ; whereas Meckel considers it probable 

 that they always have a root in the outset, 

 losing it subsequently after separation from 

 their seat of attachment. 



Tooth. Teeth are frequently found in 

 pilo-fatty cysts ; there scarcely appears, indeed, 

 to he a single authentic case of the discovery 

 of adventitious teeth (except where produced 



* This has been denied hypothetically ; yet no- 

 thing is less improbable than the occasional "growth 

 of obvious hairs from this organ, seeing that some 

 of the epithelial processes of the conical papillae 

 actually enclose minute hairs in the natural state. 

 (See Todd and Bowman, Anatomy, vol. i. p. 440.) 



t Gazelles, Journal de Med. t. xxiv. p. 332. 



j Of more than an inch in length, by Bichat. 

 Anat. Gen. t. iv. 



Ford, Medical Communications, vol. i. p. 444. 

 1784. 



|| Yet what is to be said of the case related by 

 Henry (Med. Chir. Trans, vol. x. p. 142. 1819) of 

 a middle-aged man, who voided hairs of from T ' 5 

 of an inch to an inch in length with the urine, some 

 of them occasionally coated with uric acid ? 



