55° 



NATURE 



[October 27, 1910 



deficiency of the black superficial pigments which formed 

 a conspicuous element in the coloration of normal green- 

 fed larvae during the last two stages. Several larvse fed 

 on mid-rib were practically white at the time of pupation ; 

 those fed on carrot were slightly darker. Further e.xperi- 

 ments would be necessary to show whether the deficiency 

 of black pigments was due to altered metabolism or was 

 comparable with the many cases among Geometrid and 

 Vanessid pupje, &c., in which the formation of black 

 superficial pigment-screens is subject to inhibition from 

 white or yellow backgrounds. The latter interpretation of 

 this case was regarded by Prof. Garstang as improbable 

 on the evidence available, for the mid-rib set had been 

 kept for the most part in a dark cupboard, and two of 

 these larvae, transferred, when half grown, to purple 

 cabbage in the light, had shown the same features to a 

 pronounced degree. 



In the discussion which followed, Mr. Doncaster in- 

 clined to the other interpretation, and suggested that the 

 light reflected from the alimentary canal of the specimens 

 on purple cabbage (which became blue-green after inges- 

 tion) may have had an inhibitive effect. 



Insect Coloration. 

 Mr. Mark L. Sykes exhibited specimens of various 

 insects among leaves and other natural objects, and in 

 his remarks held that the colours of these insects sup- 

 ported the view of protective coloration. Mr. G. Storey, 

 commenting on some remarks of Mr. Sykes on mimicry, 

 mentioned Prof. Punnett's e.xperiments on certain Ceylon 

 butterflies of the genus Papilio, which are supposed to 

 afford one of the most striking cases of mimicry. These 

 experiments, he thought, were bv no means sufficient to 

 overthrow the theory of mimicry, but they showed that the 

 mimickers derived little protection frorn their deception 

 from certain classes of their enemies. 



Tlic Biology of Tcleosi and Elasnwbrancli Eggs. 



Dr. W. J. Dakin confirmed the results reached by 

 Botazzi and others which indicated that the osmotic 

 pressure and salinity of the blood of marine teleosts were 

 different from that of the external medium in which they 

 lived, but were affected by changes in the salinity of the 

 water. The blood of the eel has a lower osmotic pressure 

 in fresh water than in the sea, and the blood of fresh- 

 water fishes is less saline than that of marine fishes. 



The osmotic pressure of the blood of elasmobranchs is 

 almost identical with that of the sea water in which they 

 live. 



Dr. Dakin extended his observations to the eggs of 

 certain fishes, and showed that the specific gravity of 

 plaice eggs can be altered by varying the salinity of the 

 water in which they are living. The egg-contents are 

 therefore not independent of the sea water. He also 

 showed that the salinity and osmotic pressure of the egg- 

 contents was much less than that of the medium in which 

 the eggs were living, and about the same as that of the 

 blood of the adult fish. There is therefore an equilibrium 

 between _ the sea water and the egg-contents which does 

 not consist in an equality of osmotic pressures ; while both 

 osmotic pressures are very different, a change in that of 

 the water produces a small but definite change in that of 

 the egg-contents. Death of the egg-contents destrovs the 

 conditions under which this equilibrium is sustained, and 

 the egg-contents increase in salinitv bv reason of the 

 influence of the surrounding sea water :' a corresponding 

 mcrease in specific gravity takes place, and the egg is 

 no longer able to float. 



The osmotic pressure of elasmobranch eggs is very 

 different from that of teleost eggs, though both may be 

 living in water of the same salinitv. The relation exist- 

 ing between the egg-contents of dog-fish eggs and the 

 water is the same as that between the blood of the adult 

 fish and the medium in which they live. 



Semination in the Sanderling. 



Prof. C. J. Patten has already pointed out that examples 



of the sanderling {Calidris arenaria), apparently in nuptial 



plumage, and occurring along our shores at the height of 



the breeding season, are not fully matured, their plumage 



NO. 2139, VOL. 84] 



presenting a slight difference from the true nuptial garb. 

 To this plurnage the name pre-nuptial was applied. Prof. 

 Patten found, on examining the testes of such birds, that 

 although a certain amount of spermatogenesis had taken 

 place, no real functional activity had been reached. Of 

 the sanderlings which occur on our coasts during the 

 period when they ought to be nesting, those birds not 

 pairing seem to divide into small parties and to lead a 

 sort of nomadic life from shore to shore until about the 

 end of August, when they tend to muster ; in September 

 they join company with migrants coming from northern 

 climes, the latter, as a rule, being young birds in first 

 autumn plumage. There are thus formed flocks of young 

 and partially matured birds. The fully adult birds arrive 

 about October. Prof. Patten considers that there is reason 

 to believe that other species of shore-birds take more than 

 a year to reach maturity, and that, prior to this period, 

 their desultory migratory movements correspond in the 

 main with those of the sanderling. Investigations into 

 the question of semination in these cases would afford 

 elucidation of some points of importance regarding avian 

 migration and geographical distribution. 



Anatomical .idaptations in Seals to Aquatic Life. 

 Dr. H. W. Marett Tims exhibited a series of lantern- 

 slides illustrating some of his observations on the collec- 

 tion of embryo seals obtained by the Discovery expedi- 

 tion, and directed attention to the adaptations to aquatic 

 life which these animals present. The rotation of the 

 limbs to the adult position takes place at an early stage 

 of development. The shortening of the neck is produced 

 by a great ventral curvature of the spine in the cervical 

 and anterior dorsal regions. This, too, is indicated at a 

 very early embryonic stage in both male and female. Dr. 

 Tims remarked, incidentally, that the manner in which 

 the cervical region of the skeletons of seals in our museums 

 was set up, namely, with the vertebra almost in a straight 

 line, was quite wrong. The prevention of the entrance of 

 water into the lungs is brought about by a secondary 

 growth of the posterior edge of the soft palate, which 

 becomes fused with the wall of the oesophagus. The fact 

 of the very early establishment of these modifications 

 affords an instance of what some would regard as examples 

 of the inheritance of acquired characters. 



The Temporal Bone in Primates. 

 Prof. R. J. .Anderson contributed some notes on the 

 temporal bone in primates, pointing out that the squamosal 

 shell, which has three or four ossific centres, sometimes 

 shows a separate zygomatic part and occasionally a 

 separate upper triangular part. The antero-posterior and 

 vertical measurements of the bone in several primates were 

 given ; they vary from 5:1 in Pithecia to less than 2 : i 

 in Semnopithecus. The various antero-posterior dimen- 

 sions were regarded as evidence of facial influence and the 

 vertical ones of cranial influence. 



The O.sford .Anthropometrical Laboratory. 

 Dr. E. Schuster presented some first results from the 

 Oxford Anthropometrical Laboratory. One of the most 

 interesting tests there carried out was that devised to 

 measure the power of concentration. A pattern, made by 

 pricking nine holes in a piece of cardboard, was shown 

 to the subject five times, on each occasion for only a 

 small fraction of a second. The subject was then asked 

 to make a map of it on squared paper, which he generally 

 failed to do correctly ; he was shown the pattern again five 

 times, and asked to make a fresh map, and so on until 

 he produced a correct one. It was found that those men 

 acquitted themselves best under this test who subsequently 

 did well in the final schools, and that men reading science 

 and mathematics were, on the whole, better than those 

 reading other subjects. 



The Relation of Regeneration and Developmental 

 Processes. 

 After dealing with a large number of examples illus- 

 trating this subject. Dr. J. W. Jenkinson pointed out that, 

 in development, three processes are clearly recognisable — 

 cell and nuclear division, growth, differentiation. Differ- 



