Oecurrenee. Pathogenesis. Analoinical Changes. Symptoms. 657 



Gliomata and gliosarcoinata occur as ill-dcliucd reddish growths. 

 Sarcomata and, in the horse, mehmotic sarcomata occur in the 

 actual brain substance, the growths being metastatic. The same 

 is true for carcinomata. In cases recorded by Trasbot and 

 Holterbach the primary growth was in the testicle or the mam- 

 mary gland. Isolated or multiple tuberculous growths occur m 

 the brain substance in a manner resembling true neoplasms. 



The following tumors have been observed in connection 

 with the meninges: fibromata, lipomata, angiomata, sarcomata, 

 epitheliomata, papillomata, myxomata and melanotic sarcomata. 

 Finally, dermoid cysts and odontomata occur in the brain or in 

 its immediate neighborhood. In a case recorded by Roth in a 

 goat the brain tissue was reduced to a layer a few millimeters 

 thick owing to the presence of an odontoma weighing 310 g. 

 From a clinical point of view tuberculosis of the meninges must 

 also be included, this being of very common occurrence in cattle. 



Tumors of the cranial bones may cause injury after break- 

 ing through the bones, by causing the development of exostoses 

 on the inner surface of the cranial bones or they may develop 

 directly on the inner surface of the cranium. Similar effects 

 may be produced by tuberculous growths (Moussu and Frick) 

 and bv actinomycotic lesions (Pieroni). Finally, neoplasms in 

 the neighborhood of the parotid may extend through the for- 

 amen lacerum into the cranium. 



Pathogenesis. The injurious effects of tumors in the 

 cranial cavity are due to the rise of intracranial pressure which 

 they occasion. This varies with the size of the growth and at 

 first affects its immediate neighborhood only, but owing to more 

 extensive grow^th may involve more distant portions of the brain. 

 In this wav nerve cells and fibers are subjected to pressure and 

 even destroyed. Many of the cells round about may l)e stim- 

 ulated. 



Anatomical Changes. In cases in which the tumor is in 

 the brain tissue itself the portion containing it is enlarged, its 

 convolutions flattened out and the medullary substance pale in 

 color and dry. Tumors of this kind are generally found in the 

 hemispheres,' in the cerebellum and exceptionally in the corpus 

 callosum (Cadeac), in the pituitary body (Wolff, Mollereau), 

 in the olfactory bulbs (Marchand, Petit & Coquot) and in the 

 pineal gland. Tumors in connection with the membranes or the 

 bones are, as a rule, situated about the base of the brain. Tu- 

 mors in connection wath the base of the brain not only exert an 

 effect on the brain tissue, b,ut the roots of many of the cranial 

 nerves may be also involved. 



According to Ziirn enlargement and induration of the pineal gland are mat 

 with in the fowl and the pigeon and cause cerebral disturbances. 



Symptoms. Neoplasms that are by no means small may be 

 found at the postmortem of animals wdiich have shown no symp- 



