28 THE TONER LECTURES. 



tous mass ; on the other hand a small-celled infiltration ex- 

 tends much farther from the main group along the course of 

 the blood-vessels. 



In the first instance an infiltration of small cells makes its 

 appearance between the fat cells, accompanied by an increase 

 in the quantity of the matrix b}' which they are held together. 

 The structural conditions to be observed are precisely the 

 same as may be seen in ordinary inflammation of adipose tis- 

 sue. In a report on the pleuro-pneumonia of cattle made in 

 June, 1870, and subsequently published by the Commissioner 

 of Agriculture,* I described some sections of the inflamed adi- 

 pose tissue about the pericardium, taken from a case of that 

 disease in which the appearances were precisely what I have 

 just described, and the photo-micrograph which accompanied 

 the report, but for the somewhat greater size of the fat cells 

 represented, might be supposed to have been taken from the 

 vicinity of a cancerous breast. It is not in its beginning, 

 but in the subsequent history of the small-celled infiltration 

 between the fat cells in cancer, that it diff'ers from the similar 

 small-celled infiltration in inflammation. There is no diflSculty 

 in making out this subsequent history in many of the sections 

 belonging to the Museum. The small cells infiltrated between 

 the fat cells increase in number and size, the fat cells them- 

 selves are pushed more and more apart, are more and more 

 encroached upon by the morbid growth, and finally disappear 

 without seeming to have contributed anything to the new 

 formation which has replaced them. 



Where the small-celled infiltration has extended from the 

 growth, in the course of the blood-vessels, it appears to occupy 

 primarily the walls of the small veins and the spaces between 

 the immediately adjacent fat cells. In these spaces the beha- 

 vior of the infiltration is identical with what I have just de- 



* Report of the Commissioner of Ajiriculture on the Diseases of Uattlc iu the 

 UniteJ States. Government I'riuting Office, 1871, p. G4. 



