Turning to the inhalation experiments, the quantity of dust breathed when as high as 0·0007 gramme per litre produced symptoms after only twelve inhalations for a period of about thirty-seven days; whereas when the dose was reduced to 0·0001 gramme per diem the time required to produce symptoms of poisoning was 120 days; in fact, this last dose (0·0001) for the animal under experiment was almost the lower limit, as this animal showed an almost steady line of weight for a considerable time, the weight remaining up for the first hundred days, a slight variation taking place from week to week until a progressive diminution set in. Practically all the animals poisoned manifested a very distinct diminution in body weight; in four only other symptoms of poisoning appeared first. This is a fact that is often to be noted amongst lead-workers, and if a progressive diminution in weight takes place, there is strong reason for supposing that a considerable alteration in the metabolism of the body has taken place; but it does not follow that microscopical hæmorrhages or other definite effects of poisoning are present, although such is probable. Finally, in summing up the conclusions to be drawn from the above experiments, it has been suggested that such experiments as inoculation, experimental inhalation, or even feeding, are no criterion of the circumstances under which industrial workers become infected with lead. It is perhaps hardly necessary to refer to this point, but for the fact that it is possible this book may be made use of by those who are not in the habit of dealing with experimental pathology. One of the first and most important matters in dealing with any form of poisoning is to obtain knowledge of the actual symptoms both clinically and physiologically, as well as pathologically, of the effects of any drug, and to determine if the symptoms so produced in an experimental animal conform to the symptoms as seen in man. For the purpose, therefore, an animal is required which is susceptible to the poison, and therefore cats were used in the foregoing experiments, as it is absolutely impossible to keep a domesticated cat in any white lead works, for the animals invariably become poisoned by lead.