240 MORBID STATES OP THE BLOOD, ETC. 



type in the tissue of the lymphatic glands; hence these are 

 among its most favourite localities. It begins as a simply hyper- 

 plastic enlargement ; at a later period it assumes its true character 

 as a progressive groAvth. Several subspecies may be based on 

 its variations in consistency and colour, in rapidity of growth 

 and malignity. The least malignant forms, whose growth is 

 least rapid, and whose texture is hardest, are characterised by 

 the simultaneous implication of a whole group of glands, e.g, of 

 all the glands of the upper or lower cervical fossa. A highly 

 lobulated tumour is produced, often of large size, every one of 

 whose lobes corresponds to a swollen lymphatic gland. The 

 vessels and nerves are variously dislocated, and the removal of 

 the mass by operation rendered almost impracticable in con- 

 sequence (Pseudoscrofulosis). 



A second variety, much softer than the first, and made up 

 of larger cells, is especially prone to perforate the walls of veins 

 and then to extend in their interior (cancer of veins). We some- 

 times find all the veins in the front of the neck or in the groin 

 filled with sarcomatous thrombi of this sort ; these of course afford 

 excellent materials for embolic accidents. The precise mode in 

 which this intravascular extension takes place has not yet been 

 satisfactorily ascertained. From microscopic investigation one 

 gets the idea that the first step is a coagulation of the blood, 

 and that the farther growth of the sarcomatous mass proceeds as 

 it were under cover of this clot. Others again assert that the 

 clot is directly converted into sarcomatous tissue. 



A third set of lymphadenoid sarcomata are marked by 

 their tendency to break through the limits of their parent-gland 

 at an early period, and to cause extensive infiltrations of the 

 loose areolar tissue in its neighbourhood. In rapidity of growth 

 and malignity, these tumours do not yield the palm to any species 

 of sarcoma, though they never exhibit an alveolar structure. As 

 regards treatment, they ought not as a rule to be meddled with, 

 although the observations on the fatty degeneration and absorp- 

 tion of sarcomata in consequence of intercurrent erysipelas, given 

 in § 92, referred to this very species. 



§ 209. VI. Carcinoma. One of the most interesting pro- 

 blems in histology is the discovery of the way in which a primary 

 cancer infects a neighbouring lymphatic gland ; and should the 

 a priori hypothesis, that it is due to a migration of cancer-cells 



