182 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
a more generous use of hypothesis as a scientific guide in entomology. 
Taxonomy is all very well and a useful discipline, descriptive anatomy 
supplies a necessary basis of fact, all additions to our physiological and 
embryological knowledge are most welcome, but, as Faraday said, “ let 
us encourage ourselves by a little more imagination.” In a most judicial 
way Prof. Meldola holds the balance between wanton theorising, on the 
one hand, and refusing to speculate at all, on the other. He refers to 
the fertility *of the Batesian theory of mimicry; and his own suggestion 
(1873) that variable colouring may be the result of individual adapta- 
bility due to natural selection, is, whether valid or not, another good 
case in point. Times are indeed changed since Darwin wrote (1857) 
that “ few naturalists care for anything beyond the mere description of 
species ” ; but even the author’s occasionally marked apologetic tone 
shows, were other evidence wanting, that a plea for more “ scientific use 
of the imagination ” is still relevant. “ The c bugbear ’ — speculation — 
is a very harmless animal if you look him boldly in the face ; and if you 
treat him gently and put him in harness, he will drive the chariot of 
science for you at a speed that will leave the empirical method far 
behind in the race for the knowledge of nature’s ways.” 
Physiology of the Orthoptera.* — M. L. Cuenot has continued in 
the Orthoptera the series of careful physiological researches which he 
began with the Pulmonate Gastropods and the Decapod Crustaceans. 
He has especially investigated the processes of excretion, of intestinal 
absorption, and of phagocytosis, as well as various points of interest in 
the physiology of digestion and of the blood. The method was chiefly 
by means of physiological injections and subsequent examination ; the 
types were the larger of the common orthopterous insects of southern 
and eastern France. The most important results are the following : — 
In the types examined there are three sets of excretory organs — the 
malpighian tubes, the pericardial cells, and certain cells of the corpora 
adiposa. In the last-named cells urates are stored throughout life, the 
pericardial cells apparently secrete waste-products, which are finally 
eliminated by the malpighian tubes, but do not store these waste- 
products ; the malpighian tubes are constantly eliminating waste. 
Absorption of the products of digestion takes place entirely in the mid- 
gut, and in its caeca when these are present (cf. Decapod Crustaceans). 
The mid-gut exercises a selective action on the food-constituents com- 
parable to the action of the Vertebrate liver. 
Branching of the Tracheae in the Spinning-Glands of Lepidopterous 
Larvae.! — Herr Emil Holmgren discusses the interpretation of the so- 
called ‘‘tracheal end- cells,” and gives a preliminary account of his own 
observations. While Schultze held that the tracheae terminated in these 
much-branched cells, Wielowiejski maintained that the processes of the 
so-called cells were tracheal capillaries, the cells themselves being the 
constituents of a peritoneal investment of the capillaries; recent in- 
vestigators have not determined which is the correct interpretation, nor 
have they decided whether or no the tracheae penetrate into the cells of 
the spinning-glands. By the use of methylen-blue as a “ vital ” stain, 
* Arch. Biol., xiv. (1896) pp. 293-341 (2 pis.). 
f Anat. Anzeig., xi. (1895) pp. 340-6 (3 figs.). 
