I.—On the Development of the Olfactory Organ in Protopterus

Abstract

The first definite olfactory rudiments, arising as two solid ingrowths of the deep layer of ectoderm on the under-side of the head, are to be seen in sections of Stage XXVII.A section through the left olfactory rudiment of Stage XXVIII (fig. 1) shows the early structure of the organ clearly, with its ingrowing thickening of the deep ectodermal layer covered by the thin superficial ectoderm. The cells in both layers are heavily laden with yolk particles, as illustrated in the text-figure by black dots.In the later stages, XXIX and XXX, the rudiment is similar; the cells near their outer ends are becoming progressively less yolky.