In the consideration of the subject as above, reference has been made to the effect of alcohol upon the adult system. But there can be no question that it is vastly greater and more ruinous in its effects upon the brain, when used during the period of youth and early manhood. At this time, the whole system is much more susceptible to unfavorable influences of all kinds, and especially is this the case with the brain, and that portion of it which is concerned in mentality. The more highly sensitive and delicately organized any portion, or the substance of any part of the system may be, the more easily and rapidly are impressions and changes of a permanent character made upon it. The brain, being more highly organized than any other organ or portion of the body, and the metamorphosis of its tissues being more rapid during the earlier periods of life, becomes greatly more susceptible to the bad effects of alcohol, and a diathesis is more rapidly created. And, it may be added, that, when this diathesis has once become developed during early life, there exists almost no hope of eradicating it, or of again rendering the brain healthy. Improvement may take place while abstinence from alcohol continues and the person is under restraint, but when once again the unfortunate victim is thrown upon his own resources, and left to his self-control, he always falls, and returns again to his cups, as a sow to her wallowing in the mire. In the preceding chapter upon Heredity in its relation to the Insane Diathesis, it was shown that the effects of alcohol are such, that they are most surely transmitted from parent to child; and that its effects, both moral and physical, are of the most serious character. We have now seen how it comes to pass that such is the nature of its effects. By its too frequent use there results a changed condition of the coats of the blood-vessels, and an abnormal state of the brain-cells and fibres. In accordance with the laws of heredity, a tendency to this condition is transmitted from parent to child, to the third or fourth generation, unless it be sooner eliminated, and may manifest itself in any one of the many forms mentioned, all of which are of a serious nature and generally exist through life. The importance therefore of abstinence from the use of alcoholic beverages by all parents, and especially by the young of both sexes in its relation to the subject of healthy brain action, can hardly be overestimated. No one change in the customs of society and the habits of individuals could occur, which would exert a larger influence toward the prevention of insanity. CHAPTER XI. TOBACCO. As this substance is so generally used and so often referred to in connection with alcohol as to its effects upon the human system, it appears proper to allude to its physiological effects upon the brain in this immediate connection.