No sooner has the child been ushered into the world than the breasts of the mother pour forth their milk for its sustenance. This bland fluid is secreted from the blood, and varies, in quality and quantity, according to the time which has elapsed from delivery, being peculiarly and wonderfully adapted at every period to the wants of the individual for whose use it is destined. Thus, that first secreted, called _colostrum_, possesses a purgative quality evidently intended by the all-wise Author of our being for the purpose of removing _the meconium_[A],--a process which experience has sufficiently proved to be necessary for the welfare of the newly-born infant. Afterwards, ceasing to possess this aperient property, it is calculated solely for affording nutrition; and finally, at a certain period from delivery, it gradually becomes impoverished, loses its former healthy qualities altogether, and acquires others which are injurious to life. This important change, as above noticed, generally happens at a certain period after delivery; varying, however, somewhat in particular women, and in the same female on different occasions: but, from disease, or other circumstances, the milk may become deteriorated before the time to which reference has just been made. If, for instance, the mother labour under any serious disorder, it is universally admitted that her milk may also become unhealthy; and this may take place even a short interval after delivery. Although we cannot explain how the brain and nerves act, and probably never shall be able to do so, yet we are well aware that their influence is absolutely requisite for the healthy performance of every function in the human body. That mental inquietude will impede digestion is a fact familiar to almost every one; but, I believe, it is not so generally known, that it will with no less certainty retard and alter the nature of the secretion furnished by the breasts of the lactescent female. Violent affections of the mind will cause the milk to become thin and yellowish, and to acquire noxious properties: even the fond mother's anxiety, while hanging over the couch of her sick infant, will be sufficient to render it unfit for the sustenance of the object of her solicitude. The state also of the stomach and bowels and the diet of the nurse materially and constantly influence the nature of the lacteal secretion. The milk, besides, is liable to deterioration from another cause, namely, the recurrence of the usual periodical appearance--for should this take place in a nurse, it is agreed that her milk is liable to produce disorders in the child who imbibes it; which could not happen, if the former possessed its ordinary component parts, and retained its natural properties.