ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 171 



salivary glands absent in cetaceans, yet cases like the skin-glands of 

 Myxine and Chimcera, and the buccal gland of lampreys, show that it is 

 almost impossible to make a phylogenetic series with well-defined steps. 



(Esophageal Glands in Reptiles.* — F. Beguin finds distinct oeso- 

 phageal glands in an African lizard, Uromastix acanthmurus, and in 

 Testudo grtcca, but not in the alligator. 



Histogenesis of the Intestinal Epithelium in the Frog.f — R. H. 

 Marcelin gives an account of the development of the frog's intestine — 

 its growth in length, the histogenesis of the epithelium, and the develop- 

 ment of the glands. The whole intestine is originally ciliated, and this 

 is important before the muscles causing peristalsis have developed. In 

 the buccal cavity and oesophagus the ciliated epithelium persists, aiding 

 in this region of rapid movement the action of the muscles. In the 

 stomach and intestinal regions the cilia disappear as the adult conditions 

 are attained. The calyciform cells, which appear first in the oesophagus 

 and stomach, and subsequently in the small intestine after the cilia have 

 gone, secrete a mucus which is probably both digestive and lubricating. 

 They disappear from the stomach as the gastric glands develop, they are 

 minute in the small intestine, and they disappear completely from the 

 large intestine as the strong musculature develops. 



Cardiac Muscle Fibres. X — F. Marceau discusses the transverse 

 scalariform-striated bands in cardiac muscle fibres which occur in adult 

 mammals, in young mammals some time after birth, and in certain adult 

 birds. He describes their intimate structure, their development, and 

 their distribution in the heart ; and then discusses their probable signi- 

 ficance in helping to secure rapid and rhythmic contraction. 



Egg-Tooth in Sauropsida.§ — Margherita Pondrelli finds that the 

 egg-tooth in Chelonia has the same structure and development as in birds. 

 It consists of a mass of epithelial cells, irregularly polygonal in form, 

 dovetailed together, with indurated walls, and without intercellular sub- 

 stance. It is abetted by an epitrichial thickening, which forms a cap 

 with abundant ceratohyaline. 



Minute Structure of Blood- Vessels. || — Drs. Baum and Thienel have 

 completed a laborious research on the peculiarities in the detailed struc- 

 ture of the walls of the arteries and veins in different parts of the body 

 and in different animals. They bring out very clearly the fact that 

 various mammals are quite specific as regards the walls of the vessels. 



c. General. 



Zoological Essays.lf — R. Lydekker has re-published in volume form 

 a set of his well-known and much appreciated zoological essays — fine 

 examples of the possibility of expressing accurate science in vivid 



» Anat. Anzeig., xxiv. (1904) pp. 337-56 (14 figs.), 

 t Revue Suisse Zool., xi. (1903) pp. 309-92 (1 pi.). 

 X Comptes Rendus, cxxxvi. (1903) pp. 1085-7. 

 § Anat. Anzeig., xxiv. (1903) pp. 165-8 (2 figs.). 

 || Arch. Mikr. Anat., Ixiii. (1903) pp. 10-34 (1 pi.). 



Tf Mostly Mammals. Zoological Essays. 8vo, London, 1903, ix. and 383 pp. 

 16 full-page illustrations. 



N 2 



