ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 683 



Minute Structure of Gas-Gland in the Swim-Bladder.* — Karo- 

 lina Reis and J. Nusbaum give an account of the gas-gland in Fierasfer, 

 Ophidium, Charax, Macropodus, and other Teleosteans. In its best 

 developed portion, nearest the vascular organ or rete mirabile, the gland 

 shows a layer of cylindrical epithelium with many tubular diverticula. 

 These branch, and their blind ends often fuse, the cylindrical epithelium 

 becoming cubical or polygonal at the areas of fusion. At other places, 

 where less developed, the epithelium has only a few short blind diverti- 

 cula. The secretion of the gas seems to be associated with a breaking 

 down of blood corpuscles, and granular debris is often seen in the 

 blood-vessels of the gland. The gas is secreted in the form of minute 

 vesicles in the plasma of the glandular cells ; these coalesce, and doubt- 

 less pass into the lumen of the swim-bladder. The authors describe in 

 particular the trophospongia of the cells, for the gas-gland is a very 

 suitable object for the study of this structure. 



Fat-Cells in Glandulae vesiculares of Cattle.f — (*. Illing describes 

 at the base of the secreting epithelium of the glandulae vesiculares and 

 their duct, sphere- or oval-shaped bodies about 17 fx. in diameter. They 

 form part of the glandular epithelium, and occur both as a continuous 

 and an interrupted layer. They consist of fat cells of a peculiar kind, 

 distinguished by a special arrangement, form, and size, but above all by 

 their place of occurrence, from the usual fat-cell. 



Structure of Seminal Duct in Amphibia.^ — H. Gerhartz gives an 

 account of the macroscopic appearance and histology of the seminal duct 

 and vesicle in Rana and Triton at the pairing time and throughout the 

 cycle of changes which they undergo. The involution and regeneration 

 of the seminal vesicle goes hand in hand with corresponding stages in 

 the testis of Ranafusca — i.e. it increases in size when the formation and 

 maturation of sperms begin, whilst after emission there is marked 

 retrogression. The vesicle possesses a glandular character, and its 

 secretion is to be found throughout the whole year quite independently 

 of the increase in size which accompanies the development of the testis. 

 In Triton the duct also is probably glandular. 



Structure of Wing-Feathers.§— E. Mascha has made a detailed 

 study of the minute structure of the wing-feathers of the pigeon and 

 other birds. Among the most noteworthy discoveries made are the 

 recognition of the variability in the size and structure of the secondary 

 fibres, of the importance of their ventral ridge, of the variation of the 

 hook fibres, and of the constancy of the curved fibres. According to 

 the nomenclature used, the vanes are composed of secondary quills which 

 rise obliquely from the upper part of the primary quill, and of the 

 tertiary fibres (hook-fibres and curved fibres) rising in a similar manner 

 from the secondaries. The author has much to say regarding the 

 ventral horn-ridge of the secondary quills, the complicated structures at 

 the origin of the tertiary fibres, the differences between hook-fibres and 



* Anat. Anzeig., xxvii. (1905) pp. 129-39 (2 pis.), 

 t Arch. Mikr. Anat., Bd. 66 (1905) pp. 121-7 (1 pi.). 

 \ Op. cit., Bd. 65 (1905) pp. 666-98 (4 pis.). 

 § Smithsonian Misc. Coll.. iii. (1905) pp. 1-30 (16 pis.). 



