[38] In the "avertissement" to his _Système des Animaux sans Vertèbres_ (1801), after stating that he had at his disposition the magnificent collection of invertebrate animals of the museum, he refers to his private collection as follows: "Et une autre assez riche que j'ai formée moi-même par près de trente années de recherches," p. vii. Afterwards he formed another collection of shells named according to his system, and containing a part of the types described in his _Histoire Naturelle des Animaux sans Vertèbres_ and in his minor articles. This collection the government did not acquire, and it is now in the museum at Geneva. The Paris museum, however, possesses a good many of the Lamarckian types, which are on exhibition (Perrier, _l. c._, p. 20). [39] _Lettre du Ministre des Finances (de Ramel) au Ministre de l'Intérieur_ (13 pr. an V.). See Perrier, _l. c._, p. 20. CHAPTER V LAST DAYS AND DEATH Lamarck's life was saddened and embittered by the loss of four wives, and the pangs of losing three of his children;[40] also by the rigid economy he had to practise and the unending poverty of his whole existence. A very heavy blow to him and to science was the loss, at an advanced age, of his eyesight. It was, apparently, not a sudden attack of blindness, for we have hints that at times he had to call in Latreille and others to aid him in the study of the insects. The continuous use of the magnifying lens and the microscope, probably, was the cause of enfeebled eyesight, resulting in complete loss of vision. Duval[41] states that he passed the last ten years of his life in darkness; that his loss of sight gradually came on until he became completely blind. In the reports of the meetings of the Board of Professors there is but one reference to his blindness. Previous to this we find that, at his last appearance at these sessions--_i.e._, April 19, 1825--since his condition did not permit him to give his course of lectures, he had asked M. Latreille to fill his place; but such was the latter's health, he proposed that M. Audouin, sub-librarian of the French Institute, should lecture in his stead, on the invertebrate animals. This was agreed to. The next reference, and the only explicit one, is that in the records for May 23, 1826, as follows: "Vu la cécité dont M. de Lamarck est frappé, M. Bosc[42] continuera d'exercer sur les parties confiert à M. Audouin la surveillance attribuée au Professeur." But, according to Duval, long before this he had been unable to use his eyes. In his _Système analytique des Connaissances positives de l'Homme_, published in 1820, he refers to the sudden loss of his eyesight.