330 SEROrS MEMBRANES. 



to them stand fil/romatoiis outgrowtlis. These are especially 

 prone to become polypoid. In the dropsical tunica vaginalis 

 testis, and in the peritoneal cavity, "\ve occasionally meet with 

 free fibrous bodies, varying in size from a cherry-stone to a 

 hazel-nut, of a spherical or spheroidal shape and concentrically 

 laminated structure ; these are simply the detached heads of 

 such polypoid excrescences from the walls of the cavity. The 

 softer dendritic vegetations^ which are less frequent on serous 

 than on synovial membranes, are described by Rohitanshi as 

 follows : — " Their first appearance is in the form of club-shaped 

 hyaline vesicles (minute granulations of embryonic tissue, 

 Ilindfleiscli) I these grow into an arborescent structure, and pro- 

 duce connective tissue in their interior. The clavate extremities 

 of the twigs and branches commonly become flattened into 

 lenticular or melon-seed-shaped bodies, and sometimes exhibit a 

 facetted surface. The primitive nodule often grows into a sacci- 

 form cj'st, filled with serum, or with a fibrous network whose 

 interstices contain fluid." \\q may call the latter form a pen- 

 dulous myxoma. It constitutes a transition stage to the com- 

 plete liquefaction of the contents of the nodule, which then 

 becomes a pedunculated '^ cyst due to sofi:ening " (Erweichungs- 

 cyste). The latter are most frequently met with on the perito- 

 neum, and especially on that part of it which clothes the female 

 generative organs — the broad ligaments, ovaries, and Fallopian 

 tubes. 



§ 282. The lipoma arhorescens of Midler is peculiar to serous 

 and synovial membranes. I have already pointed out in detail 

 (§ 133) the close analogy which subsists between the central 

 growth of lipomatous tumours, and the dendritic type of struc- 

 ture. We might fairly regard the Lipoma arhorescens as a lip>oma 

 tuherosmn, broken up into its component elements ; but it is 

 better to regard it simph' as a hyperplastic development of tlio 

 familiar villous and polypoid fatty appendages of the serous and 

 synovial membranes (o^^p. ejnploicce, glandidw Ilaversiance, S^'c). 



§ 283. As regards the heteroplastic formations (cancer, 

 tubercle, sarcoma) which occur either primarily or secondarily on 

 serous membranes, there is only one question which interests 

 us as histologists — that concerning the origin of the embryonic 

 tissue, which as we know, forms the common basis of them 

 all. These growths (when they really spring from the serous 



