538 General Notes. | May, 
manner as in some of the worms, and the origin of the blood 
corpuscles as nucleoli of endodermic cells. ° 
6. The existence of embryonic gills. 
7. The lack of any sharp distinction between a cell and its nu- 
cleus, and between a nucleus and its nucleolus. 
8. The existence of segmental enlargements of the mesodermic 
somites, similar to those from which the nephridia of worms take 
their origin. 
9. The origin and significance of the embryonal membranes 
among the insecta. 
10. The origin and significance of the dorsal organ among the 
sufficient number of cells to form the blastodermic membrane. 
This mode is the same as observed by Bobretsky in the Lepr 
doptera. There is no segmentation of the yolk. ell- 
The fact that at first the embryo is composed of pa 
marked regions, which the author designates as the thor 
maxillary, thoracic, and abdominal,” is interesting. The a 
does not attempt to compare this feature with the ean n 
of the spider with its protozonites, as discovered by 
but the resemblance is at least a striking one. ‘ped and 
clearly descr! ation 
figured. After giving a summary of the develope a organs. 
The novel points worked out are the origin of the her e 
discovery of so-called gills, and the relations a 
yers. ; i the 
The formation of the heart begins after the rev ee 
embryo; it is first to be distinguished in the abdom! «Jn the 
about the tirne of the closure of the dorsal pets u 
formation of the heart, the lateral plates of mesoderm an mediat 
around the mesenteron, and as their edges approach two plates 
dorsal line there is seen to be in each a tube. m on 
coalesce in the median line, and their tubes unite int 
heart, or dorsal vessel.” » which Mr. 
The discovery of the “gills or respiratory hci outgrow 
Ayers describes is rather startling. A pair he first abdo 
arise from the ectoderm of the pleural region of the 
