292 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Elastic Tissue in Eye of Birds.* — E. Wace Carlier has studied 

 this in a large number of birds. Among Vertebrates, the Sauropsida 

 alone possess striped muscle fibres within the eyeball, which, by their 

 powerful and rapid contraction, permit of a sudden change from negative 

 to positive accommodation. The shock which might be imparted ta 

 the delicate structures within the globe, might interfere with clearness 

 of definition, were not some means provided of absorbing it, and of 

 converting the sudden pull of the muscle on the choroid into an even, 

 continuous strain. This is effected by a great increase in the amount of 

 elastic tissue within the eye. When compared with the eyes of other 

 Vertebrates, the eye of a bird is seen to contain an enormous quantity 

 of elastic fibres, and to be provided with a special elastic tendon for the 

 insertion of the ciliary muscle ; this is present to some extent in lizards, 

 but no trace of such an arrangement can be found in fishes, amphibians, 

 or mammals. There is elastic tissue in the membrane of Descemet, the 

 pectinate ligaments, the ciliary ground plate, the choroid, and the 

 sclerotic, and of all this details are given. 



Kidney of Gobl^socidge.f — F. Guitel gives a detailed account of the 

 structure of the kidney in this family. Under External Anatomy are 

 described the general conformation, the large arterial and venous trunks, 

 and the relation of the pronephros and mesonephros to the skeleton. 

 The leading points treated under Internal Anatomy are the structure of 

 the pro- and mesonephros, the suprarenal capsules, urinary papillae, and 

 calculi. Nine species, representing five genera, are dealt with, and in 

 several instances both male and female types are separately considered. 



Minute Structure of the Electric Organ of Mormyrus oxyrhyn- 

 chus.J — H. Schlichter gives a full account of the electric plate, or 

 electro-plax, in this fish, discussing the inner fibrillar layer, the cortical 

 substance, the plate-processes, the rod-structures, the gelatinous sub- 

 stance of the chambers and the included blood-vessels, the nerves, and 

 the nerve-endings. 



Hearing Organ in Petromyzon.§ — ^R. Krause describes the histology 

 and relations of the ductus endolymphaticus, which is paired. A homo- 

 logising of the nerve-endings with those of the other Vertebrates appears 

 impossible at present. The labyrinth possesses, like that of Elasmo- 

 branchs and Teleosteans, seven nerve-end regions, and two cristae 

 acusticfe in the anterior and posterior ampulla ; one macula in the 

 mesial side division of the anterior and posterior ampullfe ; a papilla in 

 the sac-shaped appendage ; a macula in the so-called sacculus ; and 

 finally, a papilla in the dorsal duct. The homologies of these various- 

 structures are indicated. 



c. G-eneral. 



Gas-gland in Teleostean Fishes. || — Caroline Reis has studied this 

 organ in Macropodus, Sijngnathas, Girardinus, Trigla, Sargus, and many 



♦ Proc. Scottish Micr. Soc, iv. (1906) pp. 70-92 (4 pis.). 



t Arch. Zool. Exper., 4 ser., xxxv. (1906) No. 5, pp. 505 -69S (5 pis. aud 34 figs.)- 



X Zeitschr. wiss. Zool., Ixxxiv. (1906) pp. 479-525 (3 pis.). 



§ Anat. Anzeig., xxix. (1906) Erganzungsheft, pp. 2-57-65 (4 figs.). 



II Bull. Internat. Acad. Sci. Cracovie, 1906, pp. 771-7. 



