798 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Metamorphosis of Cyphonautes.* — M. A. Ostroumoff has investi- 

 gated the development of Memhranipora repiachowi, n. sp. and M. denti- 

 culata Busk. In the Cyphonautes stage of both the enigmatical organ 

 of Schneider is nothing but the " internal sac " filled with a substance 

 which afterwards spreads out on the surface and becomes an adhesive 

 membrane ; then the ciliated disk and the pucker-like organ of 

 Schneider are invaginated to give rise to the most essential parts of 

 the future polyp. 



Arthropoda. 

 a. Insecta. 



Natural Development of Cantharis-t — M. H. Beauregard believes 

 he has solved the problem of the mode of development of Cantharis. 

 At Aramon, near Avignon, he found some large pseudo-chrysalids of 

 a yellowish colour, among a number of cells of the hymenopterous 

 Colletes signata. Bringing them back to Paris, where he lost most of 

 them, he found that, on the 12th of May, the integument of one of 

 the two left opened along the back, and there emerged a larva, which, 

 after two or three days of activity, fell into a state of complete 

 torpidity. Fourteen days later it was transformed into a nymph, and 

 after a few days into a complete Cantharis. The larvae, then, live at 

 the expense of the Colletes, but it is not to be supposed that these are 

 the only Hymenoptera that afford them support ; various subterranean 

 insects of that order will suffice. It is probable that one larva uses 

 up the honey of several cells. The author takes the opportunity of 

 correcting the error of Neutwick that the vesicating power of Cantharis 

 is only developed after copulation. 



Formation of Ova in Pyrrhocoris.J — Dr. H. v. Wielowiefski con- 

 tributes certain interesting details to our knowledge of the formation 

 of the ova in insects; his observations were carried out upon 

 Pyrrhocoris apterus, and the main results are as follows. The ova are 

 uninucleate cells which contain within the nucleus a substance closely 

 similar to the chromatin of other cells ; these cells in the ripening 

 imago lie in the distal portion of the egg-tubes ; the yolk-duct dis- 

 plays a fibrous or finely granular appearance, and at its termination 

 spreads out into a tuft of fine threads between the follicular cells ; the 

 latter, instead of lying between the different ova, are collected to- 

 gether at the terminal extremity of the egg-tube and communicate 

 with the ova by means of yolk-ducts. 



Development of Gryllotalpa.§ — Dr. A. Korotneff finds evidence 

 that the eggs are not laid simultaneously by the female, but at more 

 or less short intervals ; the eggs are of an elongate oval form, and 

 are inclosed in two structureless envelopes of which the chorion is 

 pretty thick, and the vitelline membrane thin and quite transparent. 

 The endoderm is formed by some of the cells increasing considerably 



* Zool. Anzeig., viii. (1885) p. 219. 



t Comptes Kendus, c. (1883) pp. 1472-5., 



X Zool. Anzeig., viii. (1885) pp. 369-75. 



§ Zeitschr. f. Wiss. Zool., xli. (1885) pp. 570-604 (3 pis.). 



