ENGLISH SPARROWS. 667 
also the genital glands. With a single exception all these parts 
are already formed in the egg, their cells also arise directly from 
the cells of the embryo, and in the upper prothoracie disks, which 
are afterwards formed, there is still a continuity between the em- 
bryonal cells and those of the disks if still indirect, through the 
mediation of the nuclei of the peritoneal membrane surrounding 
the tracheze. 
It is well to remark —and it is based on a grand plan in the de- 
velopment of the imago—that only the walls of the parts referred 
to arise from the formative disks, the skin alone and not the mus- 
cles. These last owe their origin to a new process of cell forma- 
tion which generally obtains in the last half of the period of pu- 
pation, and gives the material for the development of the inner 
organs still wanting, the trachese, nerves, the fat body of the fly, 
and the genital armature. I have sought to call attention to the 
fact that we are dealing with a “free” cell formation, i. e., that 
the newly formed cells arise directly or indirectly from cells. In 
the early part of these researches it was proved that the first cells 
in the fertilized egg show a process of free cell formation, arising 
independently from some previous formative element. An objec- 
tion to this could be raised, that we have to do with an endog- 
€nous cell growth, while the whole egg should be considered as a 
cell. It is clearly shown to be in agreement with the earlier ob- 
Servations of Stein and Lubbock, that the insect egg is not the 
equivalent of a single cell, but is composed of a number of cells. 
Should this objection be laid aside, then a similar objection in the 
cell growth of the inner parts of the pupa could not arise, and if 
the relation be proved by fresh observations, then there may be a 
free cell growth in the living organism. 
( 
ENGLISH SPARROWS. 
BY THOMAS G. GENTRY. 
IN the September issue of the NaruraLisT, Dr. Brewer reviews 
lg Considerable length a small article which appeared in a previous 
_ umber, from the pen of Dr. Coues, concerning the European 
