742 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Arthropoda. 



Origin of Malpighian Tubules in Arthropoda.* — Mr. F. E. Beddard 

 points out that in a species of AcaniJiodrilus minute CEecal diverticula 

 arise at irregular intervals from the gut. They are at first tubular in 

 character, and are lined by an epithelium identical with that of the 

 intestine ; as they get further away from their point of opening into the 

 intestine they lose their tubular character and become continuous with 

 undoubted nephridial tubules, with a duct excavated in the substance of 

 their cells ; the tubules, which are at first intercellular, become afterwards 

 intracellular; they are absolutely indistinguishable from the nephridia, 

 and appear to join the general nephridial network of their segment. 

 These nephridial appendages are branched and anastomose with one 

 another, and they may certainly be compared to the anal nephridia of 

 the Gephyrea. It is only necessary to limit their number and arrange 

 them regularlj) to convert them into Malpighian tubules. 



Eye of Decapod Crustaceans and Arachnids.! — Prof. J. Carriere 

 makes a critical review of recent observations by Eeichenbach, Patten, 

 Kingsley, Bertkau, Mark, Parker, and Herrick, on the structure and 

 development of Arthropod eyes. He does not commit himself in the 

 meantime to definite conclusions, which he leads us, however, to expect 

 from a forthcoming work. 



a. Insecta. 



Function of Palps in Insects.^— Herr E. Wasmann cannot accept 

 the conclusion of Plateau that the palps are useless to gnawing insects 

 in the ingestion of food. The fact that the palps of such insects as 

 are fed bv others are reduced or completely aborted seems to show that 

 the palps must play an important part when food is independently 

 acquired. On this point the author enlarges with a good deal of detail. 

 We can only suppose what the function of the palps is ; it is probable 

 that they seek for and test suitable food ; in forms such as Atemeles or 

 Lomeclmsa, which have a semiparasitic mode of life, the labial palps are 

 reduced, while the maxillary palps are long and well developed. 



Some Coleoptera regularly use their maxillary palps as fingers by 

 means of which they push the morsel into the mouth, e. g. Hydrophilus 

 piceus ; this same species is unable to take in food when all its palps are 

 removed, while others, as Dytiscus marginalis, take food with less care. 

 If the antennse of D. marginalis are removed, that insect can find food by 

 means of its palps, but if they also are removed the creature will die of 

 hunger. 



Double Plexus of Nervures in Insects' ■Wings.§ — Dr. H. A. Hagen 



gives a photograph of a split wing of Aeschna heros. The wings of any 

 insect can be split before the membranes become closely connected; 

 the period varies with the size of the object and the temperature on the 

 day of development, but is rarely more than twenty-four hours. The 

 necessary operation is very simple ; the wing is cut off at its base and, 

 under water, is blown out by means of a small tube, and is then cut 

 along its hinder margin. It is spread out on paper or glass under water, 

 and is then carefully dried. 



* Ann. and Mag. Nat. Hist., iv. (1889) pp. 290-2. 



t Biolog. Centralbl., ix. (1889) pp. 225-34. 



X Biol. Centralbl., ix. (1889) pp. 303-8. § Zool. Anzeig., xii. (1889) pp. 377-8. 



