ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 17.1 
Ciliation of the Ectoderm of Amphibian Embryos.* — Mr. R. 
Assheton notes that although the ciliated ectoderm of the embryo and 
larva of Amphibians has been frequently noticed, Osborn and Willey 
have recently spoken of ectodermic ciliation as unknown in Craniate 
Vertebrates. 
The first signs of cilia in the frog embryo occur shortly before the 
closure of the neural folds. There is a rapid current along the external 
portion of the edges of the neural plate, but no cilia were seen on the 
portion of the neural plate which becomes the neural tube. Yet it is 
known that the cavities of the brain and spinal cord are ciliated in the 
adult. 
Mr. Assheton describes the various currents, dorsal, ventral, and 
lateral, at different stages. He objects in passing to the term “ suckers,” 
since the organs so designated are essentially mucous glands, bordered 
by strongly ciliated ridges, by the action of which exuded mucous cement 
is swept out. 
In both newt and frog the first sign of ciliation is along the edges of 
the neural plate. This is followed by a ciliated patch on the antero- 
ventral surface where the stomodaeal depression is formed. Shortly 
afterwards the whole surface becomes ciliated. 
Is the ciliation purely coenogenetic ? If so, what purpose does it 
serve ? On the whole, it is doubtless respiratory. The system associated 
with the cement-gland wafts out mucous secretion ; that associated with 
nasal epithelium and gill-filaments produces a rapid flow of water ; that 
producing a flow into the stomodaeal pit has no obvious use. 
The author suggests, but with no great confidence, that the occurrence 
of definite ciliated tracts may, in their relation to blastopore and mouth, 
be compared morphologically with certain ciliated tracts of Torncivia 
and of Echinoderm larvae. 
Development of the Peripheral Nervous System of Necturus.f — 
Miss Julia B. Platt reaches the following conclusions: — 
(1) An early differentiation of the ectoderm into three longitudinal 
ridges, with intersegmental transverse connections, forms the basis of 
the lateral line system. 
(2) The supra-orbital line of sense-organs and the ear form by direct 
modification of the primitive ridge of the dorso-lateral line. Sense-organs 
connected with the dorsal branches of the glosso-pharyngeal and vagus 
form from ridges that secondarily grow upwards from the epibranchial 
ridge, after the primitive ridges of the corresponding intersegments have 
disappeared in giving rise to mesectoderm. The infra-orbital sense- 
organs, the otic sense-organs, the lower organs supplied by the glosso- 
pharyngeal, and the organs of the epibranchial vagus develop by the 
modification of the primitive epibranchial ridge. The primitive inter- 
segmental thickening of the ectoderm, where it touches the hyomandi- 
bular pocket in the line of the gill-cleft, is directly modified into the 
hyomandibular line of sense-organs. The mandibular line develops as 
a secondary outgrowth from the hyomandibular line. The primitive 
ridge of ectoderm at the third vagus-cleft is the beginning from which 
* Quart. Journ. Micr. Sci., xxxviii. (1896) pp. 465-84 (ljpl.). 
f Tom. cit., pp. 485-547 (3 pis). 
