370 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



layer of liattened cells, the outlines of which are demonstrable by the 

 impregnation of their intercellular substance with a silver salt. The 

 tissues of the cornea, free from blood-vessels, in contact with paraffin 

 form similar flattened cells. 



The experiments show after repair is complete that the free surface 

 cells of accidental spaces in the tissues are flattened and form a pavement. 

 It follows that the second of the hypotheses mentioned above is tenable. 

 The flat cells of serous surfaces and those lining blood-vessels may 

 regenerate from deep connective tissue cells, and do not necessarily arise 

 from adjacent intact mesothelial or endothelial cells. 



Development of Pacific Herring.* — C. McLean Fraser describes the 

 spawning habits and development of Glwpm pallam, the Pacific herring. 

 The spawning occurs but once in a year, and occurs near shore among 

 bladder-wrack and eel-grass. After all sorts of enemies, such as birds 

 and fishes, have had an abundance, there would probal)ly be a million 

 eggs left to every square foot. The segmentation of the egg and the 

 general development of the various organs are dealt with. In another 

 paper t the author discusses paternal care in the Blue Cod {Ophiodon 

 elongatus), the behaviour of the young Dog Salmon {Oncorhynclms keta), 

 the diagnosis of fishes by means of their scales, and other points. 



Regeneration of Tail in Lizard. | — C. P. White has studied 

 regeneration after autotomy in Lacerta vivi2xira, and finds that there 

 is no special autotomy-site, for apparently any vertebra may be involved. 

 Autotomy takes place through the middle of the vertebra. In a fully 

 regenerated tail are found : (1) the skin and subcutaneous tissue ; 



(2) sixteen longitudinal bundles of muscles, segmented in zig-zag rings ; 



(3) fatty connective tissue in which run nerves and blood-vessels ; 

 (i) in the centre a tube of cartilage, unsegmented and continuous 

 except for some perforations through which blood-vessels pass into the 

 interior ; and (5) an epithelial tube continuous with the central canal 

 of the spinal cord, just as the cartilaginous tube is continuous with the 

 body and neural arch of the vertebra through which the fracture has 

 occurred. 



After autotomy the wound is quickly covered with new skin, beneath 

 which is a mass of spindle-cells originating apparently in the connective 

 tissue. This acts as a growing point, and cartilage, fat, and blood- 

 vessels arise from the spindle-cells. The muscle-fibres arise segmentally 

 in groups, the groups nearest the tip being least differentiated. The 

 muscles in the stump play no part. The nerve-trunks in the autotomy- 

 wound elongate as the regeneration proceeds. The central canal reaches 

 to the extreme tip of the tail just beneath the skin ; it there loses itself 

 in the surrounding cells, and is apparently developed from them ; it has 

 no connexion with the epidermis. 



* Trans. Rov. Canadian lust., xi. (1915) pp. 97-108 (2 pis.). 

 t Trans. Roy. Canadian Inst., xi. (1915) pp. 109-18 (1 p].). 

 X Rep. Brit. Assoc. Manchester, 1916, pp. 472-3. 



