Dr. Lachapelle took a very active part in the refounding of the medical legislation and in 1878 was elected a governor and the treasurer of the College of Physicians and Surgeons of the Province of Quebec, retaining an official connection with that important body almost continuously since, while for nine years he has held the position of president. At the time of the memorable small-pox epidemic in Montreal in 1885-6, when hundreds of new cases of the disease were reported daily, until the death rate claimed ten thousand victims, and when the city was practically placed in a state of quarantine in respect to the rest of the continent, Dr. Lachapelle came to the front as an outspoken and fearless advocate of the drastic measures adopted to check the disease. The contagion was spreading so rapidly throughout the country that it became necessary to take advantage of an old statute law and to create a central board of health which would apply throughout the province means for prevention and cure. Such a course had previously been adopted in Montreal. The moment the horror of the great pestilence was at an end Dr. Lachapelle proceeded to organize the forces of medical science for the conservation of the health of the people. He was chiefly instrumental in getting the provincial government to pass a law for the creation of a provincial board of health with powers coterminus with provincial bounds. Prior to that time there was only a local authority operating within restricted bounds. From that time forward the body which Dr. Lachapelle may be said to have created was to have jurisdiction over the whole province. The beneficial results of this measure were soon seen in better methods, improved sanitation and, above all, in the general vaccination of the people who had been so terribly scourged because of the lack of this preventative in 1885. For the most important and valuable work which he did in this connection Dr. Lachapelle received high encomiums from all sections of the American continent and from foreign lands as well, not the least flattering being the recognition of the French republic in 1898 which conferred upon him the Order of the Legion of Honor. With the establishment of the provincial board of health he was appointed its president, a position which he has since filled with credit to himself and great advantage to the entire province.