The Embryology of Patella 1 ) 
by X'Ltf 
William Patten Ph. D. 
from Boston U. S. A. 
I clesire to express my thanks to Prof. Clans for the 
personal kindness and generosity he has shown in placing at the • 
disposal of one who had no claims of nationality or a previous 
personal acqnaintance, the admirable opportunities for original 
investigation afforded by the Government Zoological Station at 
Trieste. 
I. Preparation of the Embryos. 
The ova are 0,12 mm. in diameter, of a blnish green color 
and perfectly opaque. A preparation of acetic acid and 
glycerine rendered them sufficiently transparent for a stndy of 
the general external characters, while it was found necessary to 
resort to artificial sections in order to elucidate the more compli- 
cated internal changes. 
A few drops of concentrated acetic acid were added to a 
watch glass fall of sea water into which the embryos were trans¬ 
ferred; if the solution is of the proper strength, which can easily 
be learned by experience, the color will change to a semi-trans¬ 
parent, dirty yellow, which in turn disappears entirely upon the 
addition of glycerine, leaving the embryo colorless with well marked 
nuclei and cell boundaries. 
*) DuriDg the preparation of this paper only a part of the literature I 
desired to consult was accessahle to me; I have, therefore simply recorded my ob- 
seryations without any attempt to make comparisons with or criticisms upon the 
works of a similar nature to my own. Theoretical considerations have also been 
excluded partly for the same reason and partly because I desire to confirm my 
opinions by further study. 
Claus, Arbeiten aus dem Zoologischen Institute etc. Tom. VI, Heft 2. ]q (149) 
