450 



NATURE 



[December 19, 1912 



numerous granules of nuclein, an albuminous sub- 

 stance rich in phosphorus. The tube is entirely im- 

 mersed in a small amount of liquid, which fills the 

 remainder of the cell. Prof. Julin then passed to 

 consider the lateral luminous organs of Cyclosalpa 

 pinnata, in which the cells are smaller than in Pyro- 

 soma. In the substance of the cell lies a convoluted 

 tube, frequently found to be broken up into vesicles. 

 The tube is traversed by a reticulum bearing many 

 nucleui granules. 



Prof. Minchin suggested that the luminous par- 

 ticles, being formed in cytoplasm, might be volutin 

 .and not chromatin, and that the tube in the cell might 

 be a schizomycete commensal or parasite. 



An Hermaphrodite Amphioxus. 

 Mr. Goodrich described, and exhibited sections of, 

 an hermaphrodite specimen of Amphioxus, found at 

 Naples in the summer of 191 1. It is an adult ripe 

 male with twenty-five gonads on each side. All these 

 are typical testes containing spermatozoa only, with 

 the exception of the ninth gonad on the left side, 

 which contains ova only, and is a typical ovary. This 

 appears to be the first instance of hermaphroditism 

 described in the Cephalochordata. 



Scottisli Sea Fisheries, 1898-1912. 



Prof. VV. C. M'Intosh held that a careful perusal 

 of various statistical returns does not lead to pessi- 

 mistic views of our fisheries, but rather bears out his 

 views as to the safety of the supply of food-fishes. 

 The herring, cod, haddock, plaice, lemon dab, sole, 

 and turbot have been in turn the subject of gloomy 

 forebodings, but the speaker maintained that not one 

 of these was on the road to extinction or even to 

 serious diminution. 



Prof. Ewart pointed out that the appliances now 

 used in fishing were more efficient than those in use 

 fifteen years ago, but, as the take of fish had not 

 increased in proportion, it seemed as if fish were less 

 abundant than formerly. 



Dr. Petersen remarked that, until statistics were 

 available for the whole of the North Sea, the problem 

 could not be fully discussed. 



Reissner's Fibre and the Subcommissural Organ in 



the Vertebrate Brain. 

 Prof. Dendv described the subcommissural organ as a 

 groove, or pair of grooves, lined by elongated, ciliated, 

 epithelial cells, and situated beneath the posterior 

 commissure. From these cells originate a large 

 number of slender fibrils — probably elongated cilia — 

 united together to form Reissner's fibre, which ex- 

 tends, as a_ high'y elastic, tightly stretched thread, 

 backwards through the brain-cavities and central canal 

 of the spinal cord to the extreme end of the latter, 

 where it is attached to a plug of connective-tissue 

 lying in the sinus terminalis. Reissner's fibre and the 

 subcommissural organ are well developed in all the 

 great vertebrate groups from cyclostomes to prim.ates. 

 Prof. Nicholls's recent researches have shown that 

 Reissner's fibre is not nervous (as it was believed to be 

 by Sargent). Prof. Dendy has suggested that the sub- 

 commissural organ might be a kind of intra-cerebral 

 sense-organ, concerned, with Reissner's fibre, in auto- 

 inatically regulating the flexure of the long axis of 

 the body. Prof. Nicholls's recent experiments on 

 fishes support this view, and further support is derived 

 from the fact that in man, with his erect posture 

 and but slightly flexible vertebral column, the sub- 

 lommissural organ is reduced to a mere vestige — the 

 mesoccelic recess — and Reissner's fibre is probably 

 .absent. 



NO. 2251. VOL. 90] 



Papers on Birds. 



Miss Laura Florence, who has examined the crops 

 of about 1800 birds, belonging to ninety-five species, 

 chiefly from agricultural land in the north-east of 

 Scotland, with the view of finding which were in- 

 jurious and which beneficial, gave a summary of her 

 results. She emphasised the need for examining 

 large numbers from different areas, and throughout 

 the year, if trustworthy information is to be forth- 

 coming. In some cases the verdict given by previous 

 investigators has been confirmed, e.g. as to the in- 

 juriousness of the house sparrow, wood pigeon, and 

 carrion crow, and as to the beneficial activity of the 

 hedge sparrow, fieldfare, lapwiner, and plovers. On 

 the other hand, there are several cases in which the 

 results up to the present do not confirm previous 

 opinions, e.g. the diet of the black-headed gull and 

 the common gull shows a striking resemblance to that 

 of the useful lapwing. 



Mr. A. Landsborough Thomson contributed a note 

 on the method of bird-marking — by a light metal 

 foot ring with inscription — applied by the Aberdeen 

 University inquiry, which has already yielded interest- 

 ing facts, e.g. records of an English-bred swallow 

 returning to the breeding place the following summer, 

 a Scottish-bred swallow returning to its birthplace 

 the following summer, a Scottish-bred song-thrush 

 migrating to Portugal in its first autumn, &c. 



The Development of the Thymus. 

 Prof. J. P. Hill communicated a resumS of observa- 

 tions by Miss E. A. Fraser and himself on the de- 

 velopment of the thymus, thyroid, and epithelial bodies 

 in the marsupial Trichosurus vulpecula, and empha- 

 sised the following points — (i) the origin of the super- 

 ficial cervical thymus, in major part at least, from 

 the ectoderm of the cervical sinus; (2) the derivation 

 of thymus iii. from the ventral as well as the entire caudal 

 wallof cleft iii., thus affording a transition, as regards 

 mode of origin, between thymus iii. of the lizard and 

 that of Eutheria ; (3) the presence of a well-developed 

 thymus iv., a feature characteristic (so far as is 

 known) of marsupials alone amongst the mammals ; 

 and (4) the lack of any topographical relationship of 

 the epithelial bodies to the thyroid. 



Fat-tailed Sheep. 

 Prof. J. C. Ewart discussed the origin of fat-tailed 

 sheep. He considered it probable that, as the large 

 inland seas common in Central Asia in prehistoric 

 times dried up, domesticated sheep, to have a chance 

 of surviving, found it necessary to store up fat as a 

 means of providing nourishment during the long, dry 

 season. In some cases fat was deposited to form fat- 

 rumped races, in others to form fat-tailed races. 

 Those individuals which, by increasing the number 

 and length of the tail vertebrae, provided most accom- 

 modation for fat would, in the struggle for existence, 

 have the best chance of surviving, as the aridity in 

 Central Asia increased. Prof. Ewart considered it 

 extremely probable that the long-tailed European 

 breeds, instead of inheriting their long tails from an 

 extinct long-tailed wild ancestor, as used to be 

 assumed, are indebted for their long and apparently 

 useless caudal appendages to fat-tailed ancestors. 

 Evidence in support of this view is afforded by the 

 fact that the fat in the tail gradually disappears when 

 a sheep of the .Afghan type is removed from the arid 

 deserts of Central Asia to Western Europe, where 

 green food is available throughout the year. 



Survey of the Fresh-water Fauna of India. 

 In his account of the survey of the fresh-water 

 fauna of India, which is now being carried out by 

 the Indian Museum, Dr. N. .'\nnandale laid great 



