ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 595 



by blending with the stronger left. The occurrence of right and left 

 primary epiphysial outgrowths has been noted by Beraneck in Lacertilia, 

 by Dendy in Hatteria, by Hill and by Locy in Fishes, by Gaskell in 

 Amnioccetes. Thus in the three lower Vertebrate classes the epiphysis 

 arises as a bilateral structure, and not as a mesial structure. Therefore 

 Cameron agrees with Dendy that " the ancestors of Vertebrates must 

 have possessed a pair of parietal eyes which may have been serially 

 homologous with the ordinary Vertebrate eyes." 



Development of Musculature and Skeleton in Spelerpes longi- 

 caudus.* — H. 8. Houghton gives an account of the origination and 

 development of the adult muscles in this common Salamander, of the 

 number and function of the transitory larval muscles, and of the rela- 

 tion between the two. He also discusses some of the developmental 

 processes in the larval skull. The paper is mainly descriptive of the 

 skeletal and muscular elements of a larva of 12 mm., with a few com- 

 parisons with Rana and Gryptobranclius. 



Circulation in Embryonic Stomach.f — Ivar Broman has observed 

 in human embryos of 5-10 mm. in length the occurrence of one, two, 

 or several branches of the ductus venosus Arrantii penetrating the pri- 

 mordium of the omentum minus and forming a dense plexus in the 

 mesodermic wall of the stomach. He has found similar veins in em- 

 bryos of pig, cat, fowl, Chelonian, and Necturus. It seems probable 

 that they occur in the embryos of all Vertebrates with a well-developed 

 stomach. In adult Reptiles similar veins ("afferent portals") occur, 

 and it is likely that the transient embryonic veins, which the author has. 

 discovered, correspond to these. 



6. Histology. 



Amitotic Division in Vertebrata.f — A. Nemiloff has made a fresh 

 study of this much discussed process. He found the most suitable cases 

 for study to be amitotic division in the giant cells of the epithelium of 

 the urinary bladder (of the mouse in particular), and in the lymphoid 

 layer of the liver of Amphibians. 



Myoblasts^ — A. Prenant discusses in the first place myoblasts in 

 general, comparing their fibrillar differentiation with the kinoplastic 

 filaments in other cells and in cell-division. He goes on to discuss the 

 numerical increase of the' fibrils by longitudinal splitting, and dis- 

 tinguishes complete and incomplete myoblasts according to the extent 

 to which the fibrillar differentiation invades the cell. It is still a 

 question whether the fibrils are formed independently in each myoblast, 

 or whether they arise simultaneously in a series of cells forming a sort 

 of syncytium. The distinction which the brothers Hertwig defined 

 between epithelial and mesenchymatous myoblasts still holds good. 



Prenant discusses in the second part of his communication the 



* Ohio Naturalist, iii. (1903) pp. 379-93 (4 pis.). 

 t Anat. Anzeig.. xxiii. (1903) pp. 390-1. 

 X Tom. cit., pp. 353-G8 (10 figs.). 



§ Arch. Zool. Exper., 4th ser., i. (1903); Notes et Revue, No. 4, pp. lii.-lxiv- 

 (12 figs.). 



