920 The American Naturalist. [October, 
‘‘Contributions to the Embryology of Asterias vulgaris.’ By 
G. W. Field 
The first of these contributions treats of the structure and develop- 
ment of the Gonophores in Rhodalia, from the Pacific Ocean. Haeckel 
regarded the animal as so unlike all other Siphonophores as to necessi- 
tate its being placed in an entirely new order,—Auronecte. Haeckel’s 
description of the structure of the female (and male) gonophores is 
shown to be in all probability erroneous. The authors conclude: 
‘<The egg-pouch must be regarded as a part of the stem where the 
growth of the cells may take place while the gonophore is developing. 
Assoon as the gonophore is formed, one of the eggs, already quite large, 
-passes into it, where it lies between the ectoderm and entoderm of the 
mambrium. Then by the disintegration of the egg-cells remaining in 
the egg-pouch, and by the formation of large entodermal folds which 
have a secretory function, the egg is rapidly nourished, and grows to 
a very large size. The whole arrangement is to secure as rapid a 
development of the sexual cells as possible,’’ as in the Hydromedusz. 
r. Conklin has studied the early stages in the development of 
Crepidula and Urosalpinx. Of the first four macromeres two meet in 
the center on a line which Rabl has called the ‘‘cross furrow’’ ; the 
other two are acute towards the center, and do not meet each other. 
‘“ By the position of the macromeres with regard to the ‘ cross furrow’ 
the first and second cleavage furrows may easily be distinguished ; 
e.g., if the egg be viewed from the formative pole, and so that one of 
the cleavage furrows is in the line of vision, the macromere to the 
right of this furrow and farthest from the „observer will be acute at its 
center if the furrow on the line of vision be the first cleavage furrow ; 
it will be obtuse,—z.e., will meet the opposite macromere in the cross 
furrow—if the furrow in the line of vision be the second cleavage fur- _ 
row. Of course the reverse would hold if the egg were viewed from the 
vegetative pole. The examination of many hundred eggs has shown 
that the position of the macromeres in reston to the cross furrows 
and to the first cleavage planes is a constant one,’ 
enan differs from Crepidula in the fact that while the four 
macromeres of Crepidula are equal in size, the four macromeres of 
Scalise are very unequal, one being much larger than the other 
three. ‘‘ Two furrows appear simultaneously, and seem to divide the 
ovum into one large sphere and two smaller ones. Really, however, 
one of the smaller spheres is not completely separated from the larger 
one, and soon after fuses with it. This smaller sphere is merely a con- 
stricted portion of the larger sphere, and contains the nucleus. Thus 


