424 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



separated from the ova, as in Coleoptera, have none of the characters 

 of vitellogenous cells. 



Ovary of Insects.* — Eitter v. Wielowiejski finds, from his studies 

 on the morphology of insects' ovaries, that, if the structural 

 characters of the terminal chamber be taken as the basis, they may 

 be divided into three groups. 



In the first we have those in which the embryonic cells which, in 

 young stages, are ccllected at the tip, are all converted into ovarian, 

 vitelline, or epithelial cells ; here we have the Diptera, Hymenoptera, 

 Lepidoptera, Geodephaga and Hydradephaga, and the Orthoptera. 



The second set contains ovaries the tip of which possesses 

 throughout life a more or less large solid mass of cells (terminal 

 chamber) ; here we have the Coleoptera (with the exception of the 

 Geodephaga and Hydradephaga) and some of the Aphididae. 



In the third group, which is represented only by the Hemiptera, 

 the tip of the ovaries has above the primitive ova a well- developed 

 mass of cells which functions as the organ of yolk-formation : 

 between its elements there project special root-like processes of the 

 maturing egg-cells. 



Heart of Insects.f — Miss Olga Poletajewa finds that the heart of 

 Bomhus is composed of five separate tubes, which form the chambers 

 of the organ, and that the most anterior of these is continued into the 

 aorta. Each tube narrows anteriorly so as to have the appearance of 

 a truncated cone, while the walls become thinner ; posteriorly it 

 enlarges; the anterior end passes into the posterior in front, and 

 each anterior end is so flattened laterally as to form a vertical cleft ; 

 the cardiac tubes are thus only united to one another at two points ; 

 the free portion forms a duct (ostium) by which the blood from the 

 abdomen enters the heart ; the internal surface of the anterior tube, 

 and the external surface of the posterior form pouch-like safety- 

 valves which regulate the movement of the blood. The heart of 

 Cimhex is formed in essentially the same way as that of Bomhus^ 

 The writer points out the differences between the accounts now given 

 and those of such entomotomists as Strauss, Newport, and Graber, 

 and describes the mode by which the heart appears to perform its 

 function ; contrary to the opinion of Strauss the first chamber does 

 not function alone as the propelling agent, and the ostia are not 

 perfectly closed, so that part of the blood does return to the abdominal 

 cavity. 



Further Observations on Optic Organs.^ — Herr J. Carriere gives 

 preliminary notices of the results of his further observations on the 

 structure of eyes. 



1. Double eyes of male insects. — In two genera of the EphemeridaB, 

 Poiamanthus and Cloe, the male has, in addition to the pair of eyes 

 which resemble those of the female, a secondary pair of brightly 

 coloured accessory and larger eyes ; similar eyes have been examined 

 in the Tipulid genus Bibio, and these have been found to differ, at 



* Zool. Anzeig., ix. (1886) pp, 132-9. f Ibid., pp. 13-5. 



X Ibid., pp. 141-7. 



