Unvaccinated but yet 'children of the vaccinated'—is any degree of immunity conferred by inheritance? However difficult of exact demonstration, the affirmative must be accepted not merely as a logical sequence of the experiments in the laboratory to which reference has been made, but by certain clinical phenomena of striking importance. For example, it is well known that among some of the immigrants touching our shores for the first time, who come from countries where the mosquito is not found, notably from English homes, the ravages produced in midsummer, when women and children especially are lodged in cheap boarding-houses, with windows unprotected by screens, the results of the attacks of the American insect upon their exposed skins are of a grade of severity unparalleled among natives of our soil. Generations of Americans have succeeded in establishing a partial immunity by the mere succession of these accidents in a long series of summers; so that while they may, and actually do, suffer from mosquito bites, the effects are far milder and without any proportion to those experienced by the immigrant. A striking illustration of this fact is recorded in the history of the Revolutionary War, when in the midst of their first summer on this soil the mercenary troops from Hesse-Darmstadt and Hesse-Cassel were so savagely attacked on their march from Trenton that whole platoons of troops were unable to distinguish objects through their swollen eye-lids, and were thus rendered wholly unfit for duty. Looking at the obverse of this proposition, every student of public hygiene is aware of the fact that truly formidable ravages of smallpox occur in epidemics attacking virgin populations, as, for example, islanders long unvisited by Europeans, where neither the individuals themselves nor their ancestors for generations have enjoyed the immunizing protection of vaccination. In these cases it is often not merely a decimation which results, but it may be a destruction of more than half of the entire population. In a few isolated instances almost every individual of a tribe or village has been cut off. Not the sins alone of the fathers but some of their safeguards are visited upon the children. The clean living that drove away leprosy from English soil and that so widely substituted the gout for the 'King's evil,' has tinctured the blood of the children of the men who fought at Naseby and learned a lesson in humanity from Howard.
It will be seen that the whole question pivots upon vaccination. It is necessary to look critically upon this means of securing immunity, for the procedure is again under the searchlight.
All said and done, vaccination is an invaluable means of securing immunity against smallpox, but it is not a perfect means. What artificial conquests of man are rounded to the perfection-point? Every one knows that the finest double-screw steel vessel that steams across the Atlantic can be crushed by a single blow of the arm of the sea if
