* * * * * THE VARYING SUSCEPTIBILITY OF PLANTS AND ANIMALS TO POISONS AND DISEASES. Much attention is being devoted to the causes which determine the aptitude or immunity with animals for maladies. This is in a general sense called medical geography, as a physician who has prescribed for patients in various parts of the world, and belonging to different races--the white, yellow, and black--has been able to note the diversities in the same disease, and the contradictions in the remedies employed. The true social peril, hardly discovered before we became aware how to conjure it, lies in those legions of animalcules or microbes that surround us and in the middle of which we live. M. Pasteur has revealed them to us as the factors in infectious diseases. Claude Bernard has demonstrated the community which exists between animals and vegetables--phenomena of movement, of sensibility, of production of heat, of respiration, of digestion even, for there are the _Drosera_ and kindred carnivorous plants. Iron cures chlorosis in vegetables as well as in animals, and chloroform and ether render both insensible. There resemblances are more striking still between animals. After Baudrimont, insects are, in presence of alcohols, chloroform, and irrespirable gases, similarly affected as man. Many maladies, too, are common to man and several species of animals; and this organic identity is best illustrated in the relationship between epidemics and epizootias, cancer, asthma, phthisis, smallpox, rabies, glanders, charbon, etc., afflict alike man and many species of animals. The differences between races are not less remarkable--odor and taste, for example. According to anthropophagy, negroes are best, and white people most detestable. Broca remarked, that, in the dissecting room, the muscles of the negro putrefied less rapidly than those of whites. It is perhaps to these anatomical differences that the diverse action of the same poison, in the case of races or species, may be attributed. On certain rodentia belladonna exercises no influence; morphine for a horse is a violent stimulant; a snail remains insensible to digitalis; goats eat tobacco with impunity; and in the Tarentin the inhabitants rear only black sheep, because a plant abounds which is noxious for white sheep. The nature of these conditions is a mystery for science. The _Solanæ_ tribe of plants furnish a principle which, as its name implies, produces consolation or forgetfulness, by acting on the tissues of the brain where resides the organ of thought; now, on the authority of Professor Bouchardat, these opiates have the less of effect in proportion as the animals possess the less of intelligence.