156 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
of wings by addition. The tendency throughout the order is towards vein 
multiplication. Additions are made upon both sides of several principal 
branches, and they conform to no one simple type. These new branches 
are preceded by tracheae ; but there are other interpolated veins de- 
veloped for mechanical advantage quite independently of the tracheae, 
and cutting across them. 
“ All the peculiarities of the intricate venation have arisen out of 
the necessity for making all the veins individually useful ; and those 
dragon flies which have been most successful in differentiating between 
the added veins are among the fleetest of winged creatures.” 
A further instalment * * * § deals with the wings of Ephemerids, which 
seem, at first sight, very different from those of any other order. A 
marked “ ceplialisation ” of the flight-function has taken place, and a 
reduction of the hind wings, sometimes ( Gsenis et al.) to nil. In a few 
genera ( Oligoneura et al.) both pairs of wings are furnished with but 
few veins, yet these are degraded and not generalised. Apart from the 
“ cephalisation ” of the flight-function, the corrugating of the wings has 
been the chief line of specialisation in this order. 
Digestion in the Meal-Worm.t — Herr W. Biedermann finds that 
the cells of the mid-gut epithelium of the larva of Tenebrio molitor show, 
in cytoplasm and nucleus, accumulations of reserve-material in the form 
of protein-granules and protein-masses ( Klumpchen ). With abundant 
nutrition the former are very abundant, but there are few of the latter ; 
in starved larvae the masses are more abundant than the larger grains. 
The mid-gut is never empty. It contains a lamellated cylinder with 
plate-like crystalloids between the lamellae. This appears to be formed 
by a wholesale expulsion of epithelial cells into the lumen of the gut. 
As to digestive ferments, the following were demonstrated : — an amylotic 
and inverting ferment ; a trypsin-like ferment affecting proteids ; and a 
fat-splitting ferment. There is also another which brings about an oxi- 
dation of the tyrosin. 
Parasites of Caterpillars.^; — M. Arnold Pictet finds reason to believe 
that caterpillars attacked by parasitic Hymenoptera and Diptera form 
their cocoon at a date much earlier than those in health, a result which 
seems rather to the advantage of the parasite. 
Chromatin Deduction in Hemiptera.§ — Dr. T. H. Montgomery, jun., 
corrects his previous statement that the second spermatocytic reduction 
division in the genus Euchistus is a transverse division of the chromo- 
somes, like the first. Further study leads him to agree with F. 0. 
Paulmier that the second reduction division is normally a longitudinal 
(equatorial) division. At the same time, it may bo, as a variation, 
transverse instead of longitudinal, which is “especially interesting as 
being a point in corroboration of the conclusion of 0. Hertwig, in oppo- 
sition to Weismann, that in reduction it is the halving of the chromatin 
mass, and not the plane of -division, which is the important result.” In 
* Op. cit., xxxiii. (1899) pp. 117-26 (figs. 69-73). 
t Pfluger’s Arch. ges. Physiol., lxxii. (1898) pp. 105-62. See Zool. Centralbl., 
vi. (1899) pp. 65-7. 
% CR. Soc. Phys. Hist. Nat. Geneve, in Arch. Pci. Phys. Nat., vii. (1899) pp. 79-80. 
§ Zool. Anzeig., xxii. (1899) pp. 76-7. Cf. this Journal, 1898, p. 73. 
