430 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tending to converge in the region of greatest flexion, in consequence 

 are replaced midway in the length of the trunk by a median vein, the 

 post-caval. 



Causes of Senility.* — C. Henry and L. Bastien state that in man 

 at senility there is a dehydration and consequent mineralisation. The 

 mechanism of dehydration is to be found in the diminution of energy 

 of the hydrolytic ferments, which fix water chemically on the nutriment 

 and render it assimilable. On the diminution in intensity of these 

 chemical actions, a part of the water held in the tissues now only by 

 capillary action, tends to evaporate, and hence the dehydration. Loss 

 in weight is further a direct result of the growing inactivity of these 

 ferments. The problem of senility thus assumes a new phase ; its solu- 

 tion becomes practicable by the co-operation of chemists and biologists. 



Fresh-water Biological Stations.! — D. J. Scourfield gives a short 

 account of what has been done in the United States and on the Continent 

 in the way of instituting Fresh-water Biological Stations. So far the 

 Sutton Broad Laboratory is the only fresh-water station that has been 

 established in this country, but it is only fair to call attention to the 

 good work which has been carried out in Scotland since 1892 by the 

 Lake Survey under Sir John Murray. Mr. Scourfield makes a well 

 justified plea for development in this direction, and just indicates what 

 an ideal fresh-water biological station should aim at. 



Tunicata. 



Tunicate Blood System.; — <M. Fernandez has studied the micro- 

 scopic anatomy and histological relations of the vascular system in Tuni- 

 cates, and discusses the phylogeny of vascular systems in general. In 

 Salpa the vessels are bounded by a thick membrane of connective 

 tissue in which cells occur. In Ascidia muscle-fibres in addition occur 

 around the larger vessels ; these fibres originally belonged to the mesen- 

 chymatous body musculature, and are not homologous with the heart 

 muscle. The blood cells in both Ascidia and Salpa are very variable in 

 shape, and numerous types may be recognised, all of which arise by 

 growth, or storing of nutrient material, or vacuolisation from small 

 amoebocytes. 



Pelagic Tunicates of the San Diego Region.§ — W. E. Ritter reports 

 on these, excepting the Larvacea. He describes Cyclosalpa baker i sp. n., 

 C. affinis, six species of Salpa, three of Doliolum (including the hitherto 

 undescribed trophozooid of D. tritonis), and Pyrosoma giganteum. 



INVEBTEBRATA. 



Mollusca. 

 "■ Cephalopoda. 



Notes on Anatomy of Cephalopoda.|| — C. Chun describes a hitherto 

 overlooked ciliated canal which opens into the end divisions of the 



* Comptes Renilus, cxxxix. (1904) pp. 811-14. 



t Journ. Quekett Micr. Club, 1905. pp. 129-36. 



t Jenaische Zeitsclir.. xxxix. (1904) pp. 323-422 (4 pie.). 



§ Univ. California Publications (Zoology) ii. No. 3 (1905) pp. 51-112 (2 pie.). 



II Zool. Anzeig., xxviii. (1905) pp. 644-54. 



