In contrast, he underlined the absence of the names of savants (Lamouroux) and 
men of letters (notably Honoré de Balzac and Charles Augustin de Saint-Beuve) 
who probably attended lectures given by Lamarck, or at least left literary 
testimony to that effect. This could be easily explained by the gaps in the 
list, which showed, and still show, the scars left by the vandalism of autograph 
collectors (4). 
 

It is astonishing to note that for a long time the precise archival leads 
provided by Landrieu concerning the list of attendants to Lamarck's Muséum 
courses were not taken up by the admirers and champions of the French 
naturalist, with the exception of Pietro Omodeo, a pioneer in the study of the 
Lamarck papers, which he examined in 1948. Omodeo pursued the study of the 
manuscript legacy left by Giosué Sangiovanni along the route plotted by 
Monticelli (5).  It was not until the 1970s that a zealous successor of Lamarck 
at the Muséum, Professor Max Vachon, aided by Georges Rousseau, declared his 
intention to take up again the study of the register of attendants where 
Landrieu had left it. For Vachon, as for Landrieu before him, the recognition of 
the role of Lamarck as a professor was intended to demonstrate that, in spite of 
his isolation, the naturalist had still enjoyed the opportunity to speaking and 
lecturing to over 1,100 pupils over a period of 26 years:
 

Can we doubt the influence of Lamarck on the youth of his day, since of the 234 
students who mentioned their age, 155 (66%) were less than 25 years old and 42 
(18%) were between 25 and 30, the number of pupils under thirty (197) thus 
representing 84% 

(4) M. Landrieu, cit. n. 2, pp.
(5) P. Omodeo, "Documenti per la storia delle scienze naturali al principio del 
diciannovesimo secolo. 1. La vita e le opere di Giosué Sangiovanni", in 
Bollettino di Zoologia, xvi, 1949, pp. 107-117, and "2. Lamarckian manuscripts", 
ibidem, pp. 131-137; "Centocinquant'anni di evoluzionismo" in Società, xv, 1959, 
pp. 833-883.