268 DISEASES OF DOMESTICATED BIRDS 
Microscopically the capsule of the tumor was found to consist of 
fibrous connective tissue containing isolated muscle bundles. The 
growth itself was made up of a zone of what may be called pre- 
chondral tissue, enclosing and grading into a mass of hyaline carti- 
lage through which ran the sternal keel. From this latter numer- 
ous irregular, bony trabecule radiated into the cartilage. 
A brief recapitulation of the microscopic observations indicates 
that the outermost, youngest zone of the tumor is made up of cells 
of fibroblastic type scattered sparsely in a collagenous intercellular 
substance. In its deeper portions this tissue is undergoing a trans- 
formation to cartilage, its cells taking the character of cartilage cells, 
while the ground substance becomes homogeneous and basic staining. 
The original tumor is well encapsulated, and seems nearly, if not 
quite, stationary. 
The growth is readily propagated in other birds by transplanting 
small bits of fresh, peripheral, neoplastic cartilage. By means of a 
trochar, the grafts are placed deep in the pectoral muscles. In 
growth resulting from the transplantation, cartilage is laid down, 
followed later by bone if the bird lives long enough. Death results 
from the tumor but rarely and in such instances the host gradually 
becomes emaciated. The tumor is not transferable to the pigeon. 
The growth may also be induced by the filtrate of a Berkefeld 
filter. The tumor tissue is ground up with sterile sand. The re- 
sulting mass is suspended in Ringer’s solution at blood heat and 
centrifugalized to free from tissue fragments. The supernatant 
fluid is passed through a Berkefeld filter of fine enough grade to re- 
tain B. fluorescens-liquefaciens. The percentage of tumors caused 
by the injection of filtrate is considerably higher when sterile in- 
fusorial earth is included. This material apparently causes a cell 
derangement favorable to tumor formation. 
SPINDLE CELL SARCOMA 
Rous observed a spindle cell sarcoma in a Plymouth Rock hen 
about fifteen months old. A large irregularly globular mass pro- 
truded from the right breast. It had developed slowly and without 
apparent involvement of the health of the host. The bird was 
anesthetized and nearly all of the growth was removed. When 
sliced it was found to have undergone a widespread coagulation 
necrosis at the center, but there was a rim of translucent, rather 
friable, yellowish pink tissue of glistening, finely striated surface. 
