No. 2.] BLATTA AND DORYPHORA. 351 
many of which recall the degenerating nuclei in the entoderm 
of Doryphora. We have the same vacuolization of the karyo- 
plasm and agglomeration of the chromatin. In the centre of 
the mass a pale, oval spot surrounds an elongated cavity (¢), 
which is almost obliterated. This cavity results from the de- 
pression o of Fig. 50 by a closing in over it of the peripheral 
edges of the dorsal organ. 
Figure 48, drawn from an advanced embryo saturated with 
clove oil, shows the condition of the different organs shortly 
before hatching.. The embryo preserves the shape of the egg, 
being much flattened laterally. The segments of the body are 
all distinctly defined. The mouth parts have become closely 
approximated, and have assumed their definite relations to one 
another. The long antennz (a/) extend as far as the two anal 
stylets (ast) in which the ventrally bent tip of the abdomen 
terminates. The different divisions of the alimentary canal, 
cesophagus. (ve), ingluvies (c), proventriculus (gz), stomach (s7), 
still containing the remains of the yolk with its degenerating 
nuclei, and rectum (7c¢), ending in the anus posteriorly, and 
surrounded by a wreath of Malpighian vessels (mpg) anteriorly, 
may be readily traced in the figure. The heart is seen as a 
delicate tube just beneath the dorsal integument. The large 
supracesophageal ganglion (cg/) connected with the large lateral 
compound eyes, in which the pigment is being deposited, fills 
the greater portion of the brain-box. One of the commissures 
is seen connecting it with the infracesophageal ganglion (27%). 
The three thoracic ganglia (g/%, ¢/4, ¢/°) are much larger than 
the six abdominal ganglia. <A large, granular, fat body (ad) is 
applied to the inner surface of pleural wall of the abdomen. 
The refractive granules imbedded in it form a chevron in each 
of the first five or six somites. Patten (38) in his preliminary 
note on A/atta thus describes the physical and chemical nature 
of these bodies: “In the embryos of A/azta, as well as in those 
of most if not all other insects, there appears in each of the 
segments at a certain time a great number of clear, highly 
refractive particles that at first might be taken for oil globules, 
and which have always been regarded as such. On more care- 
ful examination, however, it will readily be seen that this suppo- 
sition is incorrect. A number of tests have been made in order 
to ascertain the nature of these bodies, and the results show 
