4 . F. L. LANDACRE | 
Miss Platt (’93), as noted above, published a preliminary 
notice in which she traced the branchial cartilages definitely to 
the ectoderm derived apparently from the lateral body wall 
rather than from the neural crest. Her statement is rather hard 
to follow and caused her work to be criticised and possibly to 
be misunderstood. She seems to derive the mesoderm from two 
longitudinal ridges which later break up into three vertical ridges. 
The median portion of each vertical ridge proliferates mesoderm 
into the gill arch to form the cartilage of the gill arch. Ventral 
to this point the lateral ectoderm proliferates cells into the 
branchial arch to form mesoderm. Miss Platt states that the 
neural cells (neural crest?) break up into stellate mesoderm, 
whose fate she is unable to follow. She does not in her pre- 
. liminary paper introduce the terms ‘mesectoderm’ and ‘mesento- 
derm’ for mesenchyme derived, respectively, from ectoderm 
and entoderm. 
Later in the same year Goronowitsch (’93 a and b) published 
on the development of the neural crest in birds and fishes and 
asserted again the origin of mesenchyme from both the neural 
crest and the lateral ectoderm. He makes the surprising state- 
ment that the neural crest is concerned neither in the formation 
of ganglia nor nerves, but only in the formation of mesenchyme, 
a part of which latter forms the sheath of Schwann and deter- 
mines the course of growing nerves. The nerves.arise from 
neuroblasts. Goronowitsch derives mesenchyme from the ecto- 
derm in the region of the gill arch. The periaxial mesoderm 
comes from both neural crest and from the lateral ectoderm 
and is associated with the formation of the gill arch presumably, 
but he does not derive the cartilages specifically from the ecto- 
derm as Miss Platt had done. 
In 1894 Miss Platt elaborated the idea contained in her pre- 
liminary paper introducing the terms mesectoderm and mesento- 
derm for mesenchyme derived from the ectoderm and endoderm, 
respectively. She further recognizes the neural crest as con- 
tributing to the formation of mesectoderm, though the lateral 
ectoderm is its chief source. The axial mesoderm is recognized 
in this paper as coming from the endoderm, but in later papers 
