Bibliography. 173 
Genera have increased with equal rapidity. In the earliest edition of 
the Genera Plantarum, 1737, Linneus characterizes 1043 genera. 
In 1778, Reichard gives + - - 1343“ 
1789, Jussieu i - - a OOD: eth 
1807, Persoon * - - - 2308  * 
1824, Steudel af - - a BOBS vo46 
1830, Bartling  “ - - : 4872 “ 
1841, Endhcher ‘ - - et TASB wet 
1844, Laségue counts - - - FSOOu«ia 
Those who are ignorant enough to look upon this multiplication of 
- genera as a downright evil, should compare with this list the actual 
number of known species at these several epochs. Laségue estimates 
that the mean number of phanerogamous species for each genus, was, 
in the year 1753, —- - - - - - 5:06 
In 1807, - - - . - 9-13 
1844, - - - - - - 12-00 
But we cannot further notice these statistics, nor the estimates re- 
specting the probable total number of the vegetables of the globe ; which 
recent writers generally agree to place as high as 250,000. The chap- 
ter on the preparation and conservation of herbaria, is too brief to be 
of much practical use. The attention of M. Delessert was in early youth 
directed to botany by the perusal of the well known letters of Rousseau, 
which, although written at least seventy years ago, have as yet by no 
means lost their interest. It was to the mother of Delessert that these 
charming letters were actually addressed. ‘ La Petite,” for whom 
these lessons were prepared, was his eldest sister,—afterwards Madame 
Gautier. ‘Votre idée,’? Rousseau writes to Madame Delessert, 
‘“* d’amuser un peu la vivacite de votre fille et de l’exercer a l’attention 
sur des objets agreables et varies comme les plantes, me parait excel- 
lente ; mais je n’aurais jamais osé vous la proposer de peur de faire le 
Monsieur Fosse. Puisqu’elle vient de vous, je l’approuve de tout mon 
coeur, et j’y concourrai de méme.” 
A small herbarium, made by Rousseau for his young pupil, preserved 
with great care, forms an interesting part of Delessert’s vast cabinet. 
Each specimen, neatly prepared, is attached to its sheet of paper, adorn- 
ed with a red border, by means of little gilded bandelettes, and their 
names, in French and Latin, are inscribed beneath in the handwriting 
of Rousseau. 
The nucleus of the general herbarium was formed by Delessert’s 
eldest brother, Stephen, who, as early as the year 1788, began to as- 
semble and arrange the plants he collected during his travels in France, 
Switzerland, Germany, &c., as well as in Great Britain and the United 
States. But in September, 1794, Stephen Delessert was attacked by 
