From 1793 until 1818 he rarely, if ever, missed a meeting.

We have only observed in the records of this long period the absence of his name on two or three occasions from the list of those present.

During 1818 and the following year it was his blindness which probably prevented his regular attendance.

July 15, 1818, he was present, and presented the fifth volume of his _Animaux sans Vertebres_; and August 31, 1819, he was present[44] and laid before the Assembly the sixth volume of the same great work.
[Illustration: PORTRAIT OF LAMARCK, WHEN OLD AND BLIND, IN THE COSTUME OF A MEMBER OF THE INSTITUTE, ENGRAVED IN 1824.] From the observations of the records we infer that Lamarck never had any long, lingering illness or suffered from overwork, though his life had little sunshine or playtime in it.

He must have had a strong constitution, his only infirmity being the terrible one (especially to an observer of nature) of total blindness.
Lamarck's greatest work in systematic zooelogy would never have been completed had it not been for the self-sacrificing spirit and devotion of his eldest daughter.
A part of the sixth and the whole of the last volume of the _Animaux sans Vertebres_ were presented to the Assembly of Professors September 10, 1822.