710 SUMMARY OF CURRENT RESEARCHES RELATING TO 



In all other Mammals examined up to the present, the glands of 

 Brunner are pure mucous glands. They may secrete small quantities of 

 enzyme, but these are not present in sufficient quantities to be demon- 

 strable. The rabbit is unique among Mammals in possessing serous 

 components in the glands of Brunner. 



Structure of the Outer Segments of the Rods in the Retina of 

 Vertebrates.* — Arthur D. Howard finds that the outer segments of 

 the rods in the retina of the frog contain each an axial core that differs 

 from the peripheral substance, but the exact nature of this core has not 

 yet been made out. The outer segments, as demonstrated by the use 

 of polarised light, are positively anisotropic, and agree in this respect 

 with the axis cylinders of nerves. These outer segments therefore give 

 evidence of containing longitudinal fibrillge, and in some respects are 

 not unlike a cross-striped muscle fibre. 



A very successful method for obtaining unwrinkled retina? is 

 described. 



c. General- 



Marsupial Region of Marsupialia.j — Albertina Carlsson has made 

 an anatomical study of this region in a representative series of Marsu- 

 pials. Among the conclusions arrived at we may note : (1) that the 

 pouch of Echidna is homologous with the Metatherian marsupium ; 

 (2) that there is no direct relation between the development of the 

 pouch and that of the marsupial bones ; and (8) that the absence of a 

 musculus sphincter marsupii, when a pouch is present, is a degenerative 

 condition. 



Meckel's Diverticulum and Concomitant Absence of Csecal Ap- 

 pendix.:}: — Dr. Rame describes the case of a woman whose post-mortem 

 examination revealed the presence of a true ileal diverticulum (Meckel's 

 diverticulum) and the absence of an appendix vermiformis. The point is 

 that the absence of the latter, and the presence of the former, may be 

 correlated variations. 



Phylogeny of Vomerine Bones. §— R. Broom shows that the Mam- 

 malian vomer has its homologue in the " parasphenoid " of the Reptiles 

 and Amphibians, and that the so-called " vomers " of these lower forms 

 are really homologous to the dumb-bell bone (" prevomer ") of Omi- 

 thorhynchus. He discusses the steps by which the vomerine bones of 

 the higher forms have been derived from those of their Labyrinthodont 

 ancestors, and gives a useful table showing the principal modifications 

 of the vomer and prevomer in the primitive Labyrinthodonts and 

 Cotylosauria, in the Rhynchocephalian phylum, in the Chelonia, and in 

 the Theriodont phylum. 



Homology of the Lagena throughout Vertebrates. || — H. Spencer 

 Harrison corroborates, against Alexander and von Ebner, the orthodox 



* Amer. Naturalist, xxxvii., No. 440, pp. 541-50. 



t Zool Jahrb., xviii. (1903) pp. 489-506 (2 pis.). 



% Trav. Sci. Univ. Rennes, i..(1902) pp. 175-86 (3 figs.) 



§ Proc. Linu. Soc. N.S.W., xxvii. (1902, published 1903) pp. 544-60 (3 pis.). 



II Anat. Anzeig. xxiii. (1903) pp. 627-34 (3 figs.). 



