The real cause of these, as of all other primary tumours, remains shrouded in mystery. Secondary cancer is more frequent; it occurs usually in the form of little isolated tumours (nodular cancer) of varying size and greyish colour. =Symptoms.= Clinically the description, or rather the identification, of cancers of the liver is difficult, and the diagnosis particularly troublesome in cases of primary cancer. In secondary cancer (following tumour of the testicle in oxen castrated by the method of bistournage, for example) the general condition, on the other hand, is usually so affected that attention is pointedly drawn to the seat of the secondary growths. The patients lose appetite, the fæces become fœtid, and diarrhœa sets in without clear signs of enteritis. Examination of the liver always reveals hypertrophy, and sometimes sensitiveness. The patients rapidly lose flesh, become cachectic, and the proportionate number of red blood corpuscles diminishes. From the normal of six or seven millions the number may fall to one million or less, while that of the white corpuscles considerably increases. This leucocytosis, which accompanies all forms of visceral cancer, enables one to distinguish between cancer and chronic forms of diarrhœic enteritis; it must not be confused with leucæmia. Moderately developed ascites is common, in consequence of obstruction in the porto-hepatic circulation. [Illustration: $1] =The diagnosis= of cancer of the liver or biliary ducts is surrounded with difficulty, and the =prognosis= is extremely grave, because no treatment is possible. ECHINOCOCCOSIS OF THE LIVER. This term is applied to the development in the depths of the hepatic parenchyma of hydatids of _Tænia echinococcus_. The echinococcus hydatid is found in man, cattle, sheep, swine, etc. It represents an intermediate stage of development of the echinococcus tapeworm of dogs. Since this parasite develops its larval stage in man also, and further, since it is the most dangerous animal parasite found in man, it is important to thoroughly understand its life history in order to guard against infection. =Adult stage= (_Tænia echinococcus_). =Hosts.= Dog, dingo, jackal, wolf. [Illustration: $1] [Illustration: $1] [Illustration: $1]