TUMOES 87 



being of an embryonic type ; they are usually painful and 

 develop rapidly, are seldom encapsulated and invade the 

 most resistant surrounding tissues ; therefore they are im- 

 movable. .The surrounding skin is likely to adhere, the 

 regional lymph glands become infected and enlarged. Little 

 bits of the tumor from here reach the general circulation, 

 followed by secondary or metastatic deposits in internal 

 organs. When removed, they tend to recur and may lead to 

 constitutional disturbances. 



Give a histological classification of tumors. 



Microscopical study of tumors permits of two main 

 classes : 



1. Mesoblastic or connective tissue tumors. 



2. Epiblastic and hypoblastic or epithelial tumors. 



What are connective tissue tumors f 



Those which are composed mainly of mesoblastic cells, 

 exhibiting fibrous tissue (fibroma), osseous tissue (osteoma), 

 cartilaginous tissue (chondroma), mucous tissue (myxoma), 

 muscular tissue (myoma), etc. 



What are epithelial tv/mors ? 



Those which are composed mainly of epiblastic and hypo- 

 blastic cells — that is, epithelial cells ; for instance, the car- 

 cinoma. 



Beview the etiology of turners. 



1. They are due to the influence of bacteria or cocoidia 

 —a theory gaining in probability, 



2. Cohnheim's inclusion theory, viz.: During foetal de- 

 velopment more embryonic cells were produced than necessary 

 for foetal requirements. These embryonic cells which are in 



