TUMORS OF THE BRAIN AND ITS MEMBRANES. 265 



(gummata) ; they are more frequent as diffuse infiltrations. Nodular 

 syphiloma always passes from its edges very gradually into the healthy 

 brain-substance. Since such nodules become changed by atrophy, and 

 fatty metamorphosis of the cells commencing in the centre, to a sub- 

 stance resembling yellow tubercle, syphiloma has probably been occa- 

 sionally mistaken for tubercle. This may be avoided by bearing in 

 mind that, in syphiloma, the passage from the cheesy centre to the 

 broad, grayish-white, peripheral zone, is very gradual, while, in infil- 

 trated, growing tubercle, these zones follow each other more closely 

 and, in tubercles that can be turned out, they do not exist. In regard 

 to consistence, and the character of the cut surface, syphilitic infiltra- 

 tions greatly resemble old, simply sclerosed parts ; indeed, even the 

 microscope cannot always decide between them. 



Cysticerci are not very rare in the brain, and, when found, they 

 are usually in large numbers ; they generally occur in the gray sub- 

 stance. Occasionally some of these parasites are found dead, and 

 changed to a mortar-like concrement, in which some of the hooks from 

 the circle can usually be recognized. 



Echinococci of the brain are much rarer. They form large vesicles, 

 enclosed by a very delicate adventitia, with the well-known peculiari- 

 ties of which we have often spoken. 



Aneurisms of the cerebral arteries are not frequent. They chiefly 

 occur in the vessels at the base of the brain, in the arteria basilaris, 

 a. corporis callosi, a. fossae Sylvii, and in the a. communicantes of 

 the circle of Willis. In rare cases, they attain the size of a small 

 hen's egg, while usually they only reach that of a pea or a small 

 hazel-nut. 



SYMPTOMS Am> COUESE. The symptoms of cerebral tumors have 

 the greatest resemblance with those of the local diseases of the brain 

 previously described. There is no symptom, occurring during the 

 course of a cerebral tumor, that does not sometimes occur from soft- 

 ening of the brain, from abscess, or from some other local disease. 

 This resemblance cannot astonish us ; on the contrary, we could not 

 understand how it should be otherwise, since, like other local diseases, 

 a tumor of the brain destroys a circumscribed portion of the organ, 

 encroaches on the intracranial space, and interferes with the circulation 

 in the vicinity of the diseased part. Nevertheless, it is only in rare 

 cases that it is difficult or impossible to recognize a cerebral tumor, 

 and to distinguish it from an abscess, or other local disease of the brain. 

 (According to my experience during the last ten years, I must hesitate 

 about agreeing with the first part, at least, of Bamberger's assertion, 

 which I have previously quoted, where he says, " With few exceptions, 

 the diagnosis of tumors of the brain is rather a guess than a diagnosis. 



