In spite of his affection for his mother, he bore her almost sudden death very stoically, knowing as he did that the grave heart disease from which she suffered was bound to cause her increasing pain. My family became his, and the relations between him and my father became such that the latter, feeling ill and nearing his end, made him our guardian. Until the last my mother preserved for my husband a tender friendship which he fully returned. For years he bore the burden and responsibilities of the family. With my young brothers and sisters he kept up a tone of merry affection; always indulgent with them, he was anxious to neglect nothing that could be useful. Though ever led by the desire to procure happiness around him, it sometimes happened that he made a mistake in his appreciation and failed to reach his goal. The human soul is a riddle, life is complicated, and we ought not always to judge by results but by motives.... As far as I am personally concerned, his affection, kindness, and solicitude have always been unbounded. If during early years a few misunderstandings arose between us, they were due to my youthful obstinacy or to his nervous sensitiveness. We had our trials, but our friendship and deep affection emerged from them stronger and purer than ever. At a certain time, Elie, believing that happiness called me elsewhere, offered me my liberty, urging that I had a moral right to it. The nobility of his attitude was the best safeguard.... As years went on, our lives became more and more united; we lived in deep communion of souls, for we had reached that stage of mutual comprehension when darkness flees and all is light. CHAPTER XVI Metchnikoff at the age of thirty--Lecturing in Odessa University, from 1873 to 1882--Internal difficulties--Assassination of the Tsar, Alexander II.--Further troubles in the University--Resignation--Bad health: cardiac symptoms--Relapsing fever--Choroiditis--Studies on Ephemeridæ--Further studies on intracellular digestion--The _Parenchymella_--Holidays in the country--Experiments on agricultural pests. Elie Metchnikoff was now thirty years old, and his personality was fully characterised though it had not yet reached the culminating point of its development.