568 SUMMARY OF CURRENT RESEARCHES RELATING 10 



of the dissemination of pathogenic organisms by Musca domestka and its 

 non-bloodsucking allies. The evidence, both epidemiological and 

 bacteriological, for the spread of the bacillus of typhoid fever by flies is 

 reviewed, and it is shown that by their agency alone a sporadic incidence 

 in a military camp may be converted into an epidemic. In regard to 

 anthrax, cholera, and tuberculosis, experimental evidence shows that 

 bacilli may be carried on the bodies of flies, and afterwards transferred 

 to food-stuffs, and to wounded or moist surfaces. Conjunctivitis, 

 especially Egyptian ophthalmia, is most probably spread in a similar 

 manner, but bacteriological evidence on this point is lacking. 



Development of the Dragon-fly. — P. Backhoff has studied the de- 

 velopment of the copulafcory apparatus in the Zygopterous genus Agrion, 

 most of which takes place in the post-embryonic period. The larval 

 period of the Agrionidas falls into nine stages with seven moults, not 

 counting the actual emergence. The development of the copulatory 

 apparatus extends over the last three larval stages, and continues till the 

 perfect insect has attained its full development. It shows increasing 

 intensity and rapidity, so that the main development takes place just 

 before the emergence of the imago. There is no special penis muscula- 

 ture, erection being brought about by the abdominal muscles. The 

 copulatory apparatus is a hypodermic outgrowth, and as such is quite 

 independent of the embryonic limb-rudiments. It consists wholly of 

 epithelial tissue. Its development is accompanied by a partial moult. 

 The penis of Zygoptera is not connected with the sperm-capsule, but 

 communicates with the blood-lacunas of the body sinuses and ends blindly 

 on the external aspect. The copulatory organs are more primitive in 

 the Zygoptera than in the Anisoptera. The copulatory organs of the 

 Odonata must have evolved in the Permian or Triassic period. 



Study of the Honey-bee.f — E. Zander publishes the first two of a 

 series of studies on the honey-bee, Apis melliflca. The first paper con- 

 tains a full description of the development and comparative anatomy of 

 the thoracic exoskeleton of the bee and the wasp, with special reference 

 to the disputed point of the exact composition of the thorax. Both the 

 development and the anatomy show that the division of the thorax from 

 the abdomen lies between the fourth and the fifth segment, the fourth 

 being displaced forwards to form the posterior wall of the thorax, the 

 fifth forming the stalk and the anterior wall of the abdomen. The cleft 

 between the two the author regards as an extremely developed inter- 

 segmental furrow. 



In the second paper the structure and mechanism of the flight-appa- 

 ratus of the honey-bee are discussed. The author describes the compli- 

 cated flight-movements, vertical and rotatory, but rejects the conclusion 

 of Marey and others that all except the vertical movements are due to 

 the resistance of the air. He regards the synchronism of the move- 

 ments as due to the unity of the impulse, that is, of the muscular effort. 

 A detailed morpho-physiological analysis showed that all the parts of the 

 flight-apparatus are so marvellously fitted together that a single rauscle- 



* Zeitschr. wiss. Zool., xcv. (1910) pp. G47-706 (1 pi. and 29 figs.). 



t Tom. cit., pp. 507-17 (1 pi. and 8 figs.) ; pp. 517-50 (2 pis. and 6 figs.). 



