CYSTIC GROWTHS 41 



materials, and ultimately of foreign bodies. All ducts are 

 peculiarly liable to such occurrences, but the same principle 

 also applies to the initiation and incidence of many tumours 

 in tissues and organs, apart from ducts, and in such cases 

 it will be found, on histological and anatomical analysis, 

 that the pathological changes involved arise from circula- 

 tory stasis in one, more, or all of the circulations of the 

 affected parts, i.e. in any of the three circulations, the 

 blood, the lymph, or the proper neural substance, such as 

 may be seen, for instance, in aneurysm, localised oedema 

 and neuroma, in each of which the arrest of circulation, 

 or stasis, respectively, of the blood, the lymph, or the 

 neural medullary substance constitutes the starting point 

 of the pathological changes involved. In advanced cases 

 of any of these diseases, stasis of one or other of these 

 circulations leads to stasis of another, until frequently a 

 general stasis of all ensues, with complete arrestment 

 and gangrene. Small arrestive causes may, there- 

 fore, in time produce wholesale pathological arrestive 

 effects, and so are liable to be overlooked in the final assign- 

 ment of responsibility in the ante- and post-mortem 

 summing up. Flowing out of stasis in structures where 

 the vascular walls are to any degree permeable by the 

 arrested circulatory materials, or where those walls rupture 

 and permit wholesale escape of their contents, thickening, 

 consolidation, and pseudo-organisation ensue in the inter- 

 vascular and inter-histological spaces, and a general matting 

 or tumour essence is the result, which may overwhelm and 

 modify both the original structural features of the impli- 

 cated parts, as well as any preceding pathological conditions 

 effected by the earlier stages of endo- and peri-vascular 

 morbid change. Stasis of circulation in vasculatures when 

 collateral channels are easily reached and utilised by the 

 circulatory agencies is, therefore, less liable to occur 

 than in those vasculatures in which the circulatory channels 

 do not anastomose, so that the systemic nervine circula- 

 tions are peculiarly liable to suffer from the effects of stasis, 

 inasmuch as each neuronal unit of circulation is bounded 

 by its individual unbranching, encircling structures, and 

 hence is incapable of overcoming stasis of its contents, save 

 in one of two directions, viz. forwards or backwards, and 



