ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 161 



c General. 



Relation between Diameter of Nerve-fibres and their Rapidity 

 of Action.* — L. Lapique and R. Legendre find that the nerves of the 

 greatest functional rapidity, innervating the most rapidly contracting 

 muscles, have fibres with the largest diameter. The rapidity of trans- 

 mission is in proportion to the diameter of the fibres. Thus the nerve- 

 fibres to the white muscles of the rabbit, which contract quickly, have a 

 diameter of 13 fx., while those to the red muscles, which contract slowly, 

 have a diameter of 8 /x. 



Pigmentation of Skin in Primates.!— K. Toldt, jun. has found 

 that in thick-haired Primates there is considerable marking of the skin 

 hidden by the hair. It is due to pigmentation in the epidermis and 

 corium. There seems to be no constant relation in position or intensity 

 between pigmentation in the hair, in the epidermis, and in the corium. 

 There is often a marked symmetry in the integumentary pigmentation, 

 and it appears to be characteristic for genera at least. Numerous points 

 of interest are discussed, such as the occurrence of blue birth-marks in 

 man, which are due to a vestigial pigmentation of the corium. 



Ontogeny and Phylogeny of Pancreas.! — Ivar Broman calls atten- 

 tion to cases where there are accessory pancreatic glands, to the frequent 

 development of the pancreas from three primordia, to Oppel's observa- 

 tion that the pancreas of Proteus anguimus has nineteen to forty-four 

 ducts, and to other facts, which lead him to the view that in the primi- 

 tive condition of the vertebrate gut there were numerous small pan- 

 creatic glands in the vicinity of the opening of the bile-duct. 



Ciliary Mechanisms in Amphioxus, Ascidians, and Solenomya.§ 

 J. H. Orton has made a study of the function of cilia in connexion with 

 feeding. He finds that feeding in Amphioxus is effected in three main 

 ways. (1) By the maintenance of a stream of water through the 

 pharynx by rows of lateral cilia on the gill-bars ; (2) the throwing out 

 of mucus from the endostyle on to the gill-bars to serve for entrapping 

 food-particles ; (3 ) the collection of food-particles by rows of cilia on 

 the pharyngeal surface of the gill-bars ; these cilia work up the food- 

 particles with mucus into cylindrical masses, and transport these dorsally 

 into the dorsal groove, which carries the collected masses backwards into 

 the digestive tract. Thus the ciliary mechanisms on a gill-bar of 

 Amphioxus are exactly the same as those on the gill-filaments of some 

 Lamellibranchs, as Pecten, and some Gastropods, as Grepidula. The 

 ciliated tract known as the wheel-organ also effects food-collection, and 

 Hatschek's pit supplies mucus for entrapping food-particles. The gill of 

 Amphioxus functions mainly as a feeding-organ and a water-pump, and 

 probably not at all as an organ for aerating the blood. The mode of 

 feeding in Ascidians is almost exactly the same as in Amphioxus, but 



* Comptes Rendus, clvii. (1913) pp. 1163-6 (2 figs.), 

 t Zool Jahrb., xxxv. (1913) pp. 271-350 (4 pis. and 3 figs.), 

 t Verh. Anat. Ges., 1913, in Anat. Anzeig., xliv. (1913) Erganzung., pp. 14-20 

 (3 figs.). § Journ. Mar. Biol. Assoc, x. (1913) pp. 19-49 (11 figs.). 



