48 



NATURE 



[September 20, 1917 



migration period, nor does a cold spell mean a 

 lengthening of the time over which the migration 

 extends. Table 10 shows the difference of tempera- 

 ture of the migration day and that directly pre- 

 ceding it, and purports to prove that it is the 

 temperature of the moment, not that which went 

 before, which incites birds to migrate. It seems, 

 however, as if the author had somewhat confused 

 the issue ; it cannot be the temperature at the 

 point of arrival which incites the bird to begin 

 its migration in spring. After this vve have the 

 various migration dates compared for Switzerland, 

 Hungary, Bavaria, and Wiirttemberg, though as 

 the last has only three entries we think it might 

 have been omitted. 



In conclusion, the author indicates his convic- 

 tion, which is probably shared by most ornitholo- 

 gists, that the real incentive to migration is 

 not to be found in outward circumstances, but 

 must be sought in physiological conditions. The 

 outward conditions, including food, do un- 

 doubtedly have some effect upon it, but do not 

 produce the necessary impulse. Though there is 

 perhaps nothing startlingly new in this pamphlet, 

 yet it is a welcome addition to the literature relat- 

 ing to migration ; it shows much careful work, 

 and the fact that Dr. Bretscher refrains from 

 drawing more than very tentative conclusions adds 

 to, rather than detracts from, its value. Hte 

 realises that it is not possible to come to any 

 definite solution of the problem he is studying 

 without observations — and, we would add, 

 meteorological data — made over a much wider 

 field. W. E. C. 



CONTRIBUTIONS TO EMBRYOLOGY.' 



IVJ O money given by Mr. Carnegie for the 

 -'- ^ furtherance of scientific research is likely to 

 yield better interest than that invested in the 

 Department of Embryology in the Carnegie Insti- 

 tution of Washington, D.C. The nucleus of the 

 department was formed by the collection of human 

 embryos assembled by Prof. Mall when he held 

 the chair of anatomy in Johns Hopkins University, 

 Baltimore. It took Prof. Mall ten years to collect 

 his first hundred specimens ; five years to collect 

 the second hundred ; three years for the third ; and 

 two years for the fourth hundred. Since his col- 

 lection was taken over by the Carnegie Institution 

 four hundred specimens have been gathered each 

 year. The collection of material is now the most 

 extensive and the equipment the best of any em- 

 bryological department in the world. Speci- 

 mens are being gathered from all parts for 

 the study of " racial embryology " — an untouched 

 field of research. New technical procedures are 

 being introduced to enable workers to reconstruct 

 the different parts of the embryo with much greater 

 accuracy than had been previously possible. 



The two volumes here noticed contain an ac- 

 count of recent researches carried out by workers 

 attached to the department of which Prof. Mall is 

 the director. The director himself contributes 



1 "Contribution<: to Embryology." Vols. iv. and vi. (Carnegie Institution 

 of Washington, 1916-17.) 



two papers — one on the origin of the "magma 

 reticule," which is present in normal embryos, but 

 is particularly abundant, as Giacomini had noted^ 

 in pathological human embryos. His second paper 

 is a description of the condition of cyclops as seen 

 in early stages of human development. Mr. R. S. 

 Cunningham describes the development of lym- 

 phatics in the lung — a paper which is interesting 

 not only from a theoretical, but also from a practi- 

 cal point of view. Dr. Florence Sabin gives an 

 account of a prolonged series of investigations 

 concerning the origin of blood-vessels, and reaches 

 some unexpected conclusions regarding the 

 earliest blood channels which appear in the head 

 and brain. Certain channels which at first serve 

 as veins appear afterwards to be converted into 

 arteries. 



All the papers represent a high grade of work- 

 manship, and no pains or expense have been 

 spared to obtain accuracy and finish of illustration. 



A. K. 



NOTES. 



The succession of M. Painleve to the Premiership 

 of the French Government ought, even in this country, 

 to excite the interest and friendly sympathy of the scien- 

 tific world. The new Premier is a member_ of the 

 Paris Academy of Sciences, and a mathematician of 

 world-wide reputation ; besides contributing to the 

 literature of his subject, he has held, until quite lately, 

 two of the most important mathematical chairs in 

 France. To construct a similar case in our own 

 country, we should have to suppose our Prime Minister 

 to be a man like the late H. J. S. Smith, or Sir 

 William Ramsay; could anything more improbable be 

 thought of? Yet the evidence is steadily growing that 

 men of the so-called professorial type may show them- 

 selves eminently capable of directing public affairs ; 

 President Wilson is a conspicuous example, and as 

 time goes on the number of such cases is certain to 

 increase. We feel that, on behalf of English rnen of 

 science, we may congratulate, not only M. Painlev^, 

 but even France herself, on this appointment ; and we 

 confidently hope that the sequel will justify it, and 

 help to make average citizens understand the value, in 

 all national affairs, of a strictly scientific habit of mind. 



Under the heading of "New German Chemical 

 Discoveries," the Times of September 14 quotes from 

 the Neue Zurcher Zeitung a review of German activi- 

 ties in technical matters in the field of war economics. 

 It is stated that by the use of liquid sulphur dioxide 

 viscous golden-yellow mineral oils are being extracted 

 from coal; the yield, however, is small, 5 kilos, per 

 metric ton. This is equivalent to about ij gallons per 

 imperial ton, and is a striking commentary on the 

 shortage of such oils in Germany. The refining of 

 petroleum oils by this solvent had already been placed 

 I upon a commercial footing under the Edeleanu patents, 

 j but the outbreak of the war interrupted the develop- 

 ment of the process, which depends on the preferential 

 j solvent action of the liquefied gas on certain classes of 

 I hydrocarbons and sulphur compounds, enabling the 

 1 removal of those which give rise to a smoky flame, 

 i together with the objectionable sulphur compounds. 

 In a series of Howard lectures (Roy. Soc. Arts, 1916) 

 I Prof. Brame suggested the use of this solvent as being 

 I the most promising for the extraction of certain con- 

 I stituents of coal in future investigations ; it is therefore 

 j of some interest to find that commercial application of 

 I liquid sulphur dioxide is now yielding these hydro- 



NO. 2499, VOL. 100] 



