During the year 1912 I had the opportunity of collaborating in the creation of a laboratory of radium at Warsaw. This laboratory was founded by the Scientific Society of Warsaw which offered me its direction. I could not leave France to go back to my native country, but I willingly agreed to occupy myself with the organization of the studies in the new laboratory. In 1913, having improved my health, I was able to attend an inauguration fête in Warsaw, where a touching reception was given, leaving me an unforgettable memory of national sentiment which succeeded in creating useful work under particularly difficult political conditions. While still only partially recovered from my illness, I renewed my efforts for the construction of a suitable laboratory in Paris. Finally it was arranged for, and work began in 1912. The Pasteur Institute wished to be associated with this laboratory, and, in accord with the University, it was decided to create an Institute of Radium, with two laboratories, one of physics and one of biology, the first to be devoted to studies of the physical and chemical properties of the radioactive elements, the second to the study of their biological and medical applications. But, because of the lack of financial means, the construction work proceeded very slowly, and was not yet entirely finished when the war broke out in 1914. CHAPTER III In 1914, it happened, as it often had in other years, that my daughters had left Paris for their summer vacation before me. They were accompanied by their governess, in whom I had all confidence, and were living in a small house on the seashore in Brittany, at a place where there were also the families of several of our good friends. My work did not generally permit me to pass the entire vacation near them without interruption. That year I was preparing to join them in the last days of July, when I was stopped by the bad political news, with its premonitions of an imminent military mobilization. It did not seem possible for me to leave under these conditions, and I waited for further events. The mobilization was announced on August 1st, immediately followed by Germany's declaration of war on France. The few men of the laboratory staff and the students were mobilized, and I was left alone with our mechanic who could not join the army because of a serious heart trouble. The historic events that followed are known to every one, but only those who lived in Paris through the days of August and September, 1914, can ever really know the state of mind in the capital and the quiet courage shown by it. The mobilization was a general wave of all France passing out to the border for the defense of the land. All our interest now centered on the news from the front. After the uncertainties of the first days this news became more and more grave.