422 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
evidence points to the conclusion that the first division is the reducing 
division, and the second the equation division. 
Development of Food-Canal in Lower Insects.* * * § — Dr. It. Heymons 
contrasts in particular the development of the gut in Lepisma and in 
Orthoptera. In Orthoptera the definitive intestinal epithelium arises 
from the ectoderm of stomodasum and proctodaeum ; in Lepisma from 
yolk-cells. In Orthoptera its origin is bipolar ; in Lepisma multipolar. 
During development the yolk-cells of Orthoptera disappear ; in Lepisma 
the majority remain functional. The yolk-cells represent the true 
“ endoderm ” of insects. Heymons has also some notes on the Malpi- 
ghian tubules. In Apterygota entognatha they are either entirely 
absent, or they do not occur in their characteristic form. The typical 
tubular vessels make their first appearance in Apterygota ectognatha 
(Machilidae, Lepismatidae). 
j8. Myriopoda. 
Development of Chilopoda. t — Dr. R. Heymons has studied this in 
Scolopendra cingulata L., and has reached the following conclusions : — 
(1) The unpaired gonad and its unpaired (mesodermic) duct are both 
paired in rudiment. 
(2) In adults of both sexes there is a dorsal loop recognisable on the 
efferent duct, and this corresponds to the left of the two primary genital 
ducts. 
(3) The genital cavity and the lumen of the (mesodermic) efferent 
duct arise from the coelom. 
(4) As in insects, so in Chilopoda, there is an unpaired ectodermic 
terminal portion of the genital duct, from which the (two) paired 
terminal glands seem to be derived. 
(5) In Chilopoda (Epimorpha) the genital region consists of two 
segments, not of one. 
5. Arachnida. 
Sarcoptes minor. :£ — Dr. M. Carruccio gives a careful description of 
Sarcoptes minor Fiirstenberg, the itch mite of the cat, occasionally found 
on man. There are very clear figures of the external characters. 
Heliotaxis of Larval Mites.§ — Herr Fr. Thomas has made a num- 
ber of observations and experiments which go to show that the progressive 
movements of the larvae of the gooseberry mite (Bryobia ribis Th.) are 
always positively heliotactic, which appears to be of nutritive advan- 
tage. 
German Hydrachnidse.H — Another instalment of R. Piersig’s valu- 
able monograph on the Hydrachnidae of Germany has reached us. 
«• Crustacea. 
Peripheral Nervous System.1T — Herr E. Holmgren recognises the 
strength of the evidence which Nusbaum and Schreiber have afforded 
* SB. Ges. Nat. Freunde Berlin, 1897, pp. 111-9. 
t SB. K. Preuss. Akad. Wiss., 1898, pp. 244-51. 
X Boll. Soc. Rom. Stud. Zool., vi. (1897) pp. 181-90 (1 pi.). 
§ SB. Ges. Nat. Freunde Berlin, 1897, pp. 39-45. 
U Bibliotheca Zool., Heft 22 (1898) pp. 241-320 (9 pis.). 
1 Anat. Anzeig., xiv. (1898) pp. 409-18 (7 figs.). 
