ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 787 



carried along by a strong current they become suspended at various 

 depths, but none that are living lie at the bottom. The eggs rise 

 very slowly ; in one case noted it took an egg four minutes to rise 

 through 1^ in. of water. During the spawning process the water in 

 the tank became slightly clouded by the spermatozoa which were 

 spread through it. The milt is, however, shed in such a thin stream 

 under natural conditions that it is difficult to detect it. 



Development of Vascular Glands.* — M. Eetterer finds that 

 vascular glands in birds and mammals are formed by two tissues 

 which are different in origin ; one is mesodermic and forms the 

 vascular framework, the other is ectodermic or endodermic in origin, 

 and is formed of epithelial elements. The bursa fabricii becomes 

 atrophied in the adult bird, the embryonic lamellar tissue being con- 

 verted into bundles of dense cellular tissue, while the ei)ithelial 

 elements are compressed and disappear. Amygdaloid lymphatic 

 glands of mammals pass, in the adult, through altogether analogous 

 phases, or in other words, diminish in size and number. 



Simplified View of Histology of Striped Muscle-fibre.f — Mr. B. 

 Melland finds an intracellular network in the striped muscle-fibre of 

 Dytiscus, the bee, frog, lobster, crayfish, and rat ; this may be most 

 clearly demonstrated by gold staining ; it alone is stained by the 

 reduced gold and is thus easily visible. Network partitions cross the 

 fibre transversely, and more or less separate the muscle-fibre into 

 compartments ; down each compartment, and joining the dots at the 

 intersections of the fibres of the transverse network there runs a series 

 of fine rods. This network consists of an isotropous material, and is 

 more highly refractive than the rest of the muscle-substance, which is 

 anisotropous. The author thinks that the knowledge of this network 

 will explain the transverse striation and other complicated phenomena 

 presented by the muscle-fibre, while it brings into harmony many of 

 the conflicting statements of the histologists. 



Atlas of Practical Elementary Biology.J — Mr. G. B. Howes 

 has published an atlas of practical elementary biology, which ought 

 to be very useful, especially to those students who arc working with- 

 out the aid of a teacher. The first seven jilates deal with the frog, 

 including its histology and development ; the next three plates deal 

 with the crayBsh ; plates 11 and 12 with the earthworm; the snail 

 and the mussel have two plates apiece, and Hydra has one. Plate 18 

 is devoted tf) the "unicellular organisms" — Vorticella, Amnha, Pro- 

 tococcus, the yeast-plant, and the Bacteria. Plate 19 is devoted to the 

 Fungi, and plate 20 to the stoueworts ; the fern and the flowering 

 plant take us to the last or 21tli i)late. The appendix will be of use 

 t(> the Ixjginner, and the bibliography will show him how to extend 

 bis studies. There is a short preface by Prof. Huxley. 



• ComptcH RondiiH, c. (188.5) pp. 1.590-9. 

 + Qiiiirt. Joiirn. Mior. Hoi , xxv. (188.5) pp. .371-90 (1 pi.). 

 I HowcH, G. J{., 'An AtlttH of I'ractical Elementary liiolngy,' 24 pis. 4to, 

 Lon>loD, 1885. 



