174 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
which divide the depressions of the sixth somite, and each is connected 
with a nerve-filament. The hypodermis between the cuticle and base- 
ment-membrane is enormously thickened in the organs of both the sixth 
and seventh somites ; it contains a layer of small nuclei, which lie close 
under the cuticle, and each of which belongs to a narrow elongated cell ; 
other nuclei belong to large, elongated granular cells, which rest on the 
basement-membrane, and interspersed there are numerous slender nerve- 
filaments, with elongated fusiform nuclei at intervals. 
j8. Myriopoda. 
Myriopod producing Prussic Acid.* — Herr E. Haase calls attention 
to Paradesmus gracilis C. L. Koch, which is found endemic in many 
parts of the world, and has become established in some gardens in 
Europe. The formation of the acid was first demonstrated by C. 
Guldensteeden-Egeling, and the anatomy of the secreting organs made 
out by E. Weber. 
7, Prototracheata. 
Movements of Peripatus.j — Herr E. Haase gives an account of some 
observations on the movements of Peripatus capensis. SjDeaking gene- 
rally, they call to mind the movements of the Eijdopoda, and especially 
of the Craspedosornata. Before beginning to move, the animal often 
raises its head and the next one or two succeeding segments and puts 
its tentacles in movement ; if they are withdrawn quickly there is often 
a simultaneous contraction of the body. Like the Chilopoda, and 
especially Geopliilus, Peripatus can move as well backwards as forwards. 
The line of movement on blackened paper is quite straight, whereas in 
Chilopods the body makes distinct lateral curves. When moving, the 
feet touch the ground at a much sharper angle than, for example, in 
Lithohius. The movements of Scolopendrella appear to be quite similar 
to those of Peripatus. As in Myriopod s, the legs of a small group of 
segments alone move, while the others remain still ; if a joimq, Peripatus 
is repeatedly touched it rolls up, like the larva of one of the Tenthredi- 
nidae ; a young specimen was able to climb up vertical glass walls, but 
it could not hold on to the lower surface, a proof that its power of 
attachment is not due to the secretion of a sticky material. These 
creatures are able to move very quickly. 
When the movement was slow, Herr Haase observed five waves of 
movement through the series of legs, just as he had observed in Chilo- 
gnatha ; wlien the young moved rapidly the movements of the legs were 
so rapid as to recall galloping movements, such as are made by cater- 
pillars. In the larger specimens there are alternate movements, legs 1, 
4, 7 of one side being often followed by 2, 5 of the other. 
5. Araclinida, 
Development of Hydrachnida.J — Herr F. Koenike finds that the 
sexes of Hydrachnids may, during the developmental stages, be recog- 
nized by differences in size. After the last ecdysis increase in size 
occurs in all parts excej)t the maxillary organs, palps, epimera, feet, and 
=*= SB. Gesell. Natnrf. Freunde, 1889, p. 97. f T. c., pp. 148-51. 
X Zool. Auzeig., xii. (1889) pp. 652-5. 
