Tumors 



319 



When the filtered extracts of this tumor were injected into 

 susceptible individuals a rapid growth of cartilage forming 

 connective tissue elements took place. These growths soon 

 became cartilaginous and finally bony. 



The connective tissue tumors (especially the sarcomas) 



Fig. 71. — The growth shown in the preceding photograph after it had 

 been sawed open. Scattered amid the smooth whitish cartilage is much 

 bone with red marrow. (After Rous and Murphy.) 



are of frequent occurrence in mammals, and a large number of 

 the avian tumors which have been described belong to this 

 group. These tumors are sometimes benign but are often 



