572 SUMMARY OF CURRENT RESEARCHES RELATING TO 



a wry close agreement between Ptisanula and Diaphana, and the two 

 may be kept apart from other Scaphandridae and ranked (probably aim ig 

 with Xr/riifsiti) in a distinct family Diaphanidaa. 



Arthropoda. 



Phagocytic Reaction in Arthropods.* — W. R. Thompson has 

 inquired into the occurrence of a phagocytic reaction on the pari "I 

 insects and crustaceans to multicellular parasites (such as Hvmenoptera, 

 Diptera, Cirripedes, Nematodes and Acanthocephala), and to artificially 

 introduced bodies such as insect larvas. He finds that there is usually 

 no phagocytic reaction in such cases. If the phagocytes accumulate 

 around the parasite it is because the latter has determined a local 

 destruction of the tissues or because it is dead. It is possible that the 

 phagocytes may affect the invader by means of substances which they 

 introduce into the blood of their host, but this has not been proved. 

 Toxic substances may be produced by the elements of various tissues. 

 The protective role of the chitinous cuticle may be correlated with a 

 poorly developed phagocytosis. 



a. Insecta. 



Reproduction and Sex-dimorphism in Insects.f — Antonio Berlese 

 has worked out a theory of reproduction and sex-dimorphism, with 

 particular reference to insects. In Protozoa there is often a succession 

 of agamic reproductions on the part of anasomatic individuals, but this 

 may be interrupted by sexual or gametic reproduction. In Metazoa the 

 individual is at one time an anasomatic element or gonocyte ; it develops 

 into a heteroplastid histone. There may be alternation of agamosomes 

 and gamosomes, and the former may in certain cases be incorporated 

 along with the latter. A diagrammatic notation is introduced to 

 express the different modes of reproduction. Among insects there may 

 be reproduction at the ovum level (polyembryony), or in the larval 

 stage (psedogenesis), or in adult life. The primary condition of sex- 

 dimorphism is to be sought in the reproductive cells which determine 

 the nature of the gamosome. In the " struggle for reproduction " 

 those variations have been seized upon and established which have 

 conduced to the more effective performance of the characteristic func- 

 tions of the two sexes. A classification is given of the various secondary 

 sex characters in insects, e.g. ornamental, seductive, provocative, signal- 

 ling, accessory to copulation ; and illustrations are given of the very 

 varied degrees of sex-dimorphism. But we cannot do more than direct 

 attention to the general tenor of Berlese's paper. 



Olfactory Sense in Honey-bee.:}: — N. E. Mclndoo gives a detailed 

 account of the structure and distribution of the olfactory pores in the 

 honey-bee, which has a very acute sense of smell. This sense is most 

 highly developed in the drones and least developed in the queen, while 

 that of the worker is scarcely inferior to that of the drone. Olfactory 



* Bull. Soc. Zool. France, xl. (1915) pp. 63-8 (1 fig.). 



t Redia, x. (1915) pp. 77-112 (6 figs.). 



X Journ. Exper. Zool., xvi. (1914; pp. 265-346 (24 figs.). 



