To revert to children. They are much more susceptible than grown people to all noxious influences. They are affected by the same things, but much more quickly and seriously, viz., by want of fresh air, of proper warmth, want of cleanliness in house, clothes, bedding, or body, by startling noises, improper food, or want of punctuality, by dulness and by want of light, by too much or too little covering in bed, or when up, by want of the spirit of management generally in those in charge of them. One can, therefore, only press the importance, as being yet greater in the case of children, greatest in the case of sick children, of attending to these things. That which, however, above all, is known to injure children seriously is foul air, and most seriously at night. Keeping the rooms where they sleep tight shut up, is destruction to them. And, if the child's breathing be disordered by disease, a few hours only of such foul air may endanger its life, even where no inconvenience is felt by grown-up persons in the same room. The following passages, taken out of an excellent "Lecture on Sudden Death in Infancy and Childhood," just published, show the vital importance of careful nursing of children. "In the great majority of instances, when death suddenly befalls the infant or young child, it is an _accident_; it is not a necessary, inevitable result of any disease from which it is suffering." It may be here added, that it would be very desirable to know how often death is, with adults, "not a necessary, inevitable result of any disease." Omit the word "sudden;" (for _sudden_ death is comparatively rare in middle age;) and the sentence is almost equally true for all ages. The following causes of "accidental" death in sick children are enumerated:--"Sudden noises, which startle--a rapid change of temperature, which chills the surface, though only for a moment--a rude awakening from sleep--or even an over-hasty, or an over-full meal"--"any sudden impression on the nervous system--any hasty alteration of posture--in short, any cause whatever by which the respiratory process may be disturbed." It may again be added, that, with very weak adult patients, these causes are also (not often "suddenly fatal," it is true, but) very much oftener than is at all generally known, irreparable in their consequences. Both for children and for adults, both for sick and for well (although more certainly in the case of sick children than in any others), I would here again repeat, the most frequent and most fatal cause of all is sleeping, for even a few hours, much more for weeks and months, in foul air, a condition which, more than any other condition, disturbs the respiratory process, and tends to produce "accidental" death in disease.