_Causes._ Slowly progressive compression of the cord has been already noted as resulting from caries and other diseases of the vertebræ. It remains to notice such as result from the growth of tumors and other neoplasms in the spinal canal. In the horse these are commonly melanoma (in white horses), sarcoma, encephaloid, papilloma, cholesteatoma, and osteoma; in cattle, beside tubercle and actinomycosis, have been found sarcoma, lipoma, osteoma and glioma; and in dogs sarcoma and chondro-sarcoma. Chronic abscesses may be met with in all animals determining the same class of symptoms by slow pressure. In the same manner exudates in process of organization contract, and are liable to compress the myelon. Cadeac draws attention to a calcic degeneration of exudates in the dura mater of the dog (ossifying pachymeningitis), and of ossification of the intervertebræ cartilages with vegetations on their surfaces. Parasites also exercise a growing pressure, especially echinococcus, in cattle cysticercus mediocanellata, in sheep and dogs cœnurus, and in pigs and dogs cysticercus cellulosa. =Melanoma.= In gray and white horses, with disseminated melanosis, the spinal canal is often involved, the pigmentary sarcoma appearing in small formations and sometimes large enough to determine injurious pressure. In the early stages these may cause stiffness and lameness referable to particular muscles or groups, varying in situation, even as to the limbs affected, at successive dates, and finally merging into paraplegia. =Cholesteatoma= is less common than in the encephalon, yet one is reported by Dexler as attached to the pia mater and possessed of great firmness, crisply crackling under the knife. It doubtless secures accretions under meningeal exudates like those of the choroid plexus. =Sarcoma= and =encephaloid= are usually found in connection with the dura mater, and of small size, but numerous. They often surround the roots of the spinal nerves, and here as on the cord exert sufficient pressure to impair nervous function. =Papilloma= has been found connected with the pia mater and of marked vascularity. The author has found one in the ewe in a case of the neurasthenia of advanced gestation. =Lipoma= is also rare. Osseous growths are common, being favored by sprains and injuries. All show a marked predilection for the lumbar and last dorsal vertebræ. This may be partly explained by the liability to injury and to disease invasion through the interlocking of the joint surfaces of the rings. _Osteophytes_ growing from the intervertebral cartilage are common in the dorsal region as well. =Glioma= has been found in cattle, occupying the substance of the cord itself and growing to the size of a hen’s egg or even of the closed fist. The cord is gradually atrophied and paraplegia is inevitable. =Chrondro-sarcoma= has been found growing from the intervertebral fibro cartilage of dogs.