ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 373 
Tlie relatively small germinal streak develops ventrally ; the rela- 
tively extensive extra-embryonic area is covered by very large flat cells 
(= serosa-cells). In the middle of the embryonic disc a dark spot 
appears where the mesoderm cells wander into the interior. The very 
early incurving of the germinal streak into the yoke is noteworthy. It 
can hardly be doubted that this had to do with the development of the 
amnion. The amnion-cavity has a persistent amnion-pore, secondarily 
closed by a chitinous membrane produced by the serosa. As regards 
the segmentation of the body, the results confirm what has been estab- 
lished in Orthoptera and Odonata ; indeed, the resemblances between 
the entire development of Lepisma and that of Orthoptera are very 
close. At the end of embryonic development, the head acquires a 
brownish chitinous egg-tooth, which serves to open the shell. The 
young larva is whitish ; even the eyes are but slightly coloured. It 
seeks out a daik corner and subsists for some days on its yolk. On the 
seventh day the first moulting occurs. The differences between the 
larva and the adult, though relatively trivial, are quite distinct, and are 
duly enumerated. 
The author proceeds to a description of the development of par- 
ticular parts. We can only notice a few points. (1) The styles do 
not arise until some time after hatching ; they develop from a part 
of the body which has directly arisen from rudiments of embryonic 
appendages. (2) The origin of the mesoderm and its derivatives, though 
in some respects peculiar, bears a strong resemblance to what is known 
in Orthoptera. (3) The ganglion-cells are formed, as in Orthoptera, 
from large neuroblasts which appear in the neural ridges on each side 
of the deep and narrow neural groove. There is at first but a slight 
development of the longitudinal commissures of the nerve-chain ; even 
when the young form leaves the egg, the whole ventral cord is a con- 
tinuous strand. (4) The tracheae are late in developing. Besides the 
meso- and meta-thorax, the first nine abdominal segments have stigmata, 
and even the tenth segment has a hint of one. As the adult has only 
ten (Grassi), the ninth abdominal stigma is probably lost. The appear- 
ance of stigmata or stigma-rudiments beyond the eighth abdominal 
segment is a primitive character. (5) The genital cells make their 
appearance very early. There is no evidence of homology between 
gonapophyses and appendages. (6) The origin of the mid-gut is quite 
different from that in Orthoptera. It is formed from the yolk-cells. 
In two concluding chapters, the author points out particularly (a) 
the resemblance between the development of Lepisma and that of 
Orthoptera, and (6) the bearing of his observations on some vexed 
questions in the comparative morphology of insects. 
Development of Campodea.* — Dr. H. Uxel continues his pre- 
liminary account of the development of Campodea staphylinus Westw. 
The most important results are the following : — (1) On the intercalary 
(pre-maxillary) segment of the embryo there are appendages which 
form part of the oral apparatus in the adult, namely the intercalary 
lobes. (2) Each of the rudiments of appendages on the second to seventh 
abdominal segments gives origin to a ventral style and to an eversible 
vesicle. (3) The tergites of the maxillary segments take but little part 
* Zool. Anzeig., xx. (1897) pp. 125-8, 232--7. 
