258 DR. BEALE, ON THE TISSUES. 



to be adverse conditions, tliat mechanical separation into nu- 

 merous parts serves but to increase the rapidity of the pro- 

 duction of separate, independent organisms. 



When we consider how very greatly the normal tissues of 

 the higher animals vary in structure, properties, and power, 

 we shall not feel surprised at the great differences observed in 

 the morbid growths which originate in them. Some of these 

 grow very slowly, others very rapidly — some form circum- 

 scribed and comparatively isolated masses, while others bur- 

 row in every direction, invading every tissue in their imme- 

 diate neighbourhood, and growing at its expense. A part of 

 a morbid growth may be cut off from nutrient material by the 

 growth of the rest, and may die. Into this dying or dead 

 portion part of the living mass may grow, and, as it were, 

 live upon the very tissue which once formed a living part 

 of the whole, and of which, in fact, the last is a direct extension. 



The larger the growth becomes the greater seems to be its 

 powers of resistance, and the more readily do the normal struc- 

 tures yield to its advance. The least particle of it will spread 

 rapidly, its increase appearing to be limited only by the sup- 

 ply of nutrient material. The faster it grows the more irre- 

 sistible the power of growth seems to become, and, especially 

 in cases where the groAvth is composed of a number of loosely 

 connected portions, even a very small piece detached and 

 carried to a distant part will readily grow. In not a few 

 cases a very minute portion of the germinal matter of one of 

 these structures may be carried away to a distant part of the 

 body, and so powerful is its tendency to animate any form of 

 nutrient matter in the organism, so unrestricted the condi- 

 tions under which it grows, and so increased is its power of 

 resisting the action of conditions which would doubtless have 

 destroyed the germinal matter fi-om which it originally sprung, 

 that it will grow wherever it may chance to become station- 

 ary. An elementary part, or even a little of the germinal 

 matter, may be detached from the original mass, and removed 

 to distant parts by the movement of organs one on the other, 

 or it may be carried a long way from the point where it origi- 

 nated by the lympathic vessels, and, there can be little doubt, 

 by the blood-vessels also. 



These morbid structures may ultimately be found growing 

 in connexion with healthy tissues with which they have no 

 characters in common. A bone-germ, detached from a soft, 

 rapidly growing, spongy, bony tumour, may take root even in 

 the pulmonary tissue, and thus several hard, solid, separate 

 masses of bony structure, which may attain considerable size, 

 may grow in different parts of the lung. 



