ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 37 



the nucleus of the head and the tail ; the distal corpuscle descends, 

 along the tail as a minute granule. In the atypical series the central 

 corpuscles form the axial body and the caudal cilia, which together 

 correspond to the intracellular and extracellular fibrils of other Proso- 

 branchs. J.A.T. 



Eyes of Gastropods. — Hanna Eisenmank (Zool. Anz'eiger, 1920, 

 51, 14o-5.s, 10 figs.). A comparison of the eyes of terrestrial Gastro- 

 pods {Helix and Arion) and fresh-water Gastropods {Faludina) as 

 regards shape, lens and retina. The eye is spherical in Helix and Arion, 

 an elongated pear-shape in Paludina. The innervation is rather dif- 

 ferent. The differences in lens, retina, cornea and external envelope are 

 discussed. J. A. T. 



Arthropoda. 



a. Insecta. 



Fertilization in the Honey-Bee. — George H. BisHor {Journ. 

 Exper. Zool., 1920, 31, 225-G5, 3 pis., 3 figs.). The drone is not 

 sexually mature at the time of emergence of the imago, but grows for at 

 least 9 to 12 days. The sperm and the mucus of the accessory gland 

 change in character and behaviour as development goes on. They 

 remain separate till copulation. The partition separating them from the 

 ejaculatory duct, consisting of the chitinous lining of the blind end of 

 that duct, does not break through until copnlation. Then the sperm 

 and mucus are forced out of their receptacles by contraction of the 

 muscular walls of these organs. The musculature of the whole base of 

 the gland is so arranged as to cause, on violent contraction, the shutting 

 off of the distal portion of the gland from the proximal by a muscular 

 valve. The mucous content is thus closed off from its outlet through 

 the ejaculatory duct : at the same time sperm is allowed to pass through 

 the vas deferens and basal portion of the gland into the ejaculatory 

 duct. This spermatic fluid is thus the first to be ejaculated. The 

 mucus follows, forcing all the sperm out, and coagulating into a plug. 

 The penis is torn out in copulation. The bulb and elastic end of the 

 ejaculatory duct do not act as a spermatophore, although after copula- 

 tion, and while still attached to the queen, they may hold what remains 

 of mucus. The drone's reproductive organs are very easily stimulated 

 to contraction ; picric acid solution inhibits this, other acids provoke it. 



J. A. T. 



Insemination of Queen-Bee. — George H. Bishop {Journ. Exper. 

 Zool, 1920, 31, 2G7-S6, 2 figs.). The result of copulation is not the 

 immed^iate filling of the final sperm reservoir, the seminal receptacle of 

 the queen, but the reception of the spermatic fluid (from the seminal 

 vesicles of the drone) and the mucus (from his accessory glands). The 

 spermatozoa alone enter the spermotheca, all of them in about six and 

 a half hours. Their progress is not wholly passive ; it is possibly 

 guided Ijy chemotaxis. The mucus forces up the spermatic fluid and by 

 coagulation seals up the torn end of the copulatory organ, preventing 

 back flow. A description is given of the face-to-face coition, the 

 tapering end of the ejaculatory duct adjoining the bulb being everted 



