LAMARCK. luscus; in the third he includes, 11. Pisces, 12. Reptilia, 13. Aves, 14. Mammifera. The two first groups comprehend those treated of in this work, and his divisions are in general very judicious, though we must object to his term apathetic as applied to his first group.
The doctrine of appetence is again stated in the introduction to this work; and, to support his views on this subject, he maintains that the animals of former geological epochs were less perfect in their structure than their existing congeners; but surely the curious forms of fishes described by M. Agassiz as occurring in the oldest strata containing vertebrate remains are as perfect as those of any existing species; and the elaborate sculpture on the dermal plates of the extinct genera pamphractus, cephalaspis, or asterolepis, or the mechanical contrivance by which the armour of the pterichthys, or the scales of ganoid and ctenoid fishes of the former world are fitted to their bodies, or the groovings on the remarkable remains termed ichthyoduroloites, do not exhibit any mark of less perfect workmanship than we find in the existing creation.
Nor can we subscribe to his ideas regarding some of the apathetic animals (as he terms them). The infusoria he represents as destitute of a mouth or a digestive apparatus, and as nourished merely by imbibition through pores on their bodies, as wholly without a will, and as moving only by the action of external forces on their irritability. But the researches of Ehrenberg have proved that infusoria are more numerous, and more complex in their organization, than had been before imagined. In Ehrenberg's first class, polycistaria, he has described 552 species; and in the second, rotatoria, 170; or in all 722 well ascertained species. In the first class he has ingeniously proved the existence of a very complicated digestive apparatus, especially in the genera vorticella, epistylis, and opercularia, and in one of these no less than 120 stomachs or ventricular appendages; while in the class rotatoria he has detected eyes in 150 species. Ehrenberg has shown that they swallow food with avidity, and evidently make choice of certain aliment in preference to another, which is certainly an act of volition, while some of their movements are evidently produced by their will. In describing the medusaria, a tribe of radiate animals, Lamarck asserts that they are destitute of control over their own movements, "being without the possibility of directing them." This, however, we have ascertained to be incorrect, by experiments made purposely to ascertain this point. On a calm day, on the Clyde, opposite to the Cumbernauld, we anchored a boat where medusaria, especially Ephyra simplex and Cyanea cyclonota abounded, and saw them repeatedly change the line of their progression, when slightly tapped on the apex of their umbrella with a fishing-rod. The motion was sometimes downwards, sometimes upwards, or horizontal; and we succeeded even in thus causing them to stem the gently flowing current of a commencing flood-tide by the contractions of the edges of their disks.
Notwithstanding these objections to some of the hypothetical views of this able philosopher, we consider that this great work of Lamarck has most materially contributed to the advancement of zoology. He will ever be considered as one of our great luminaries on the INVERTEBRATA, especially in the five classes of what he terms the sensible animals; and the second edition of it, with the notes of Deshayes and Milne-Edwards, of 1835-45, is the best existing manual of the general subject in any language.
Lamarck's last scientific labour was his Mémoires sur les Coquilles, in the Annales du Museum, a very valuable treatise on shells, in which he was assisted by Valenciennes and his daughter Mademoiselle Lamarck.
M. Lamarck died at Paris in 1829, in the eighty-sixth year of his age. (T. S. T.)