The thyroid not only protects us against the poisons in meat, but also against many others; in fact, perhaps we may say, against poisons generally. Let us, however, specially mention those poisonous products which have been tried experimentally. That the thyroid protects the body against bacillary attacks has been noted by Charrin in the case of dogs, which succumb in a very short time to all kinds of infection after the removal of the thyroid. We have demonstrated, in Chapter III, the protective action of the gland against such poisons as chloroform, as mentioned in our communication to the Paris Biological Society in 1906, where we stated that in chloroform narcosis all the characteristics of an increased activity of the thyroid are perceived,—including symptoms such as we see in Graves’s disease. We have also found that the thyroid of dogs contains an increased amount of colloid substance after chloroform narcosis, which enables us to understand why this drug is not well borne by animals operated upon as above, as discovered by Lanz and by Walter Edmunds; likewise, we may thereby explain why patients suffering from Graves’s disease of long standing, in which there generally is a transition to a myxœdematous condition, are liable to a fatal termination after an operation with anesthesia. Cases of diabetes (in accord with frequency of thyroid changes) also often present serious phenomena after an operation under anesthesia, including coma and even death. Alcohol also acts on the thyroid gland, there being a certain analogy between intoxication by chloroform and by alcohol. The changes in the thyroid after the long-continued use of alcohol are the consequences of the frequent conditions of hyperactivity of this gland, expressive of its antitoxic action. We have referred to the influence of alcohol on the thyroid in other parts of this book. This gland also protects us against injurious drugs. Hunt, of Washington, has shown from experiments that when certain animals, such as rabbits, have been given acetonitril and thyroid preparations at the same time, they do not become poisoned; whereas when they have taken the former alone, they do. Jeandelize and Perrin have also proved the protective action of the thyroid against arsenic. Garnier has also found that certain drugs, such as iodine, pilocarpin, etc., when injected into animals, produce an increase of colloid secretion in the thyroid glands. It is, therefore, but logical to regard this hyperactivity of the thyroid gland as an expression of its defensive action against toxic products (see Chapter III).