THE EMBRYOLOGY OF BLATTA GERMANICA 
AND DORVPHORA DECEMLINEATA. 
WILLIAM M. WHEELER. 
TuE following study of the development of the cockroach and 
potato-beetle was taken up during the summer of 1887. On 
the suggestion of Dr. W. Patten, without whose stimulating 
friendship and assistance the work would not have been under- 
taken, I began with A/atta as a form calculated to help me to a 
knowledge of the fecundative changes in the Hexapod egg. Dr. 
Patten kindly placed at my disposal the results of his own work 
on S/atta, in the form of much carefully prepared material and 
some figures, which I have incorporated in Plate III. (Figs. 43, 
45 to 47, 52). 
Later I concentrated my attention on Doryphora, which I 
found to be a much more profitable object of study than A/azta, 
especially as far as the more advanced stages were concerned. 
Thus it happens that my remarks on odgenesis and fecundation 
are more complete in 4/a¢ta, while my account of the germ-layers 
and subsequent stages is carried into greater detail in Doryphora. 
I have seen fit to treat of both insects as nearly as possible 
under single headings, instead of describing them independently 
in two chapters, because they differ strikingly in all the details 
of development, while their main ontogenetic features are as 
strikingly similar. By running both descriptions as nearly as 
possible in parallel lines, the contrasting details are made more 
salient, while the general remarks may be taken up at intervals 
and not reserved ev masse till the end of the paper. 
PREPARATION. 
There are three common species of Blattide in Southeastern 
Wisconsin: Periplaneta orientalis (Linn.), Platamodes unicolor 
(Scud.), and Alatta germanica (Linn.). The first and the last 
occur, as is well known, about houses; the second is abundant 
under the bark of decaying logs and stumps in open woods. 
