By the term hydatid tumors in the brain, we mean the intra-cranial occurrence of either the echinococcus or the cysticercus cellulosæ in man. The former is the embryo of the tænia echinococcus which has never been known to attain maturity except in the dog. The latter is the embryo of the tænia solium, which is most frequently found in man, the hog, and the rabbit, but not unfrequently in the dog and the common rat; and has been known to exist in the ape, the bear, and the deer.
The history of these strange parasites is only tracable to the oblivion of the unknown; before the time of Aristotle they were known to be associated with hydatid tumors, and were so regarded by Hippocrates; although it was left for Pallas to describe the echinococcus as a separate parasite, in 1766, and for Göze to observe the same of the cysticercus
REED RH. HYDATID TUMORS IN THE BRAIN.. JAMA. 1885;V(1):1-5. doi:10.1001/jama.1885.02391020007001