310 SUMMARY 01' CURKENT RESEARCHES RELATING TO 



Hybrids of Peacock and Cochin-china Hen.* — G. Pays-Mellier and 

 E. Trouessart record the successful hybridisation of Pavo cristatus var. 

 nigripennis £ and Gallus gallus var. sinensis ?. The male parent was 

 the more prepotent. 



The authors remark that the hybrid of Pavo cristatus and NumMa 

 meleagris has been known for long, and they refer to Gallus x Nurunl" 

 and to the crossing of Phasianus with the nearly allied genera Chryso- 

 lophus, Genweus, and Catreus, and with the more distant genera Gallus, 

 Acomus, Lophwa, and Tragopan. The alleged crossing of Crax alberti 

 and the fowl seems doubtful. 



Fasting Powers of the Swift.j — Albert Hugues refers to Brehm's 

 statement that a swift can fast for six weeks, and relates some of his own 

 observations, the most striking case being that of a fast of 21 days less 

 3 hours, during which the weight decreased from 57 to 21 grm. 



Air-sacs of Pigeon.^: — B. M tiller has made a study of the morphology 

 of the air-sac system of the pigeon, with a view to throwing more light 

 on the problem of its function. After giving a description of the 

 methods by which he succeeded in hardening the air-sacs in a rela- 

 tively distended condition, and in obtaining an idea of the relative degrees 

 of expansion during the various phases of breathing, the author gives a 

 general account of the air-sac system, its distribution, and its relation to 

 the diaphragmatic membranes. The pulmonary and abdominal dia- 

 phragm, the lungs, the ostia, and the different air-sacs with their diver- 

 ticula, are then described in detail, followed by a critical consideration of 

 the most important hypotheses as to the function of the air-sacs. The 

 author concludes that their importance as respiratory organs has been 

 over-rated, and believes that their effect is mainly mechanical. He 

 regards them as structures selectively developed for the purpose of in- 

 creasing the size of the thorax without increasing its weight, and for 

 facilitating the movements of the organs in it, especially the heart. The 

 air-spaces are not organs with a positive function, but rather empty 

 spaces whose value lies in their emptiness, and their shape is of no im- 

 portance, their asymmetry being simply due to the asymmetry of the spaces 

 they have to occupy between the viscera. The connection with the lungs 

 is a consequence of their phylogenetic development, and has no physio- 

 logical significance other than that they assist in renewing the air in 

 the trachea. A copious bibliography is appended. 



Head-muscles in Sauropsida.§ — F. H. Edgeworth has investigated 

 the head musculature in Gallus and other Sauropsida. The distinctive 

 features of birds as compared with living reptiles are set forth in detail. 

 Birds resemble the Rhynchocephalia in possessing an upper portion of 

 the mandibular myotome inserted into the pterygoid process, but the 

 adult condition in the latter group is clearly a secondary modification 

 correlated with a fixation of the ptery go-quadrate. These are features 



* Comptes Rendus, cxlv. (1907) pp. 1203-5. 



t Bull. Soc. Zool. France, xxxii. (1907) pp. 106-8. 



t Smithsonian Misc. Coll., 1. (1907) pp. 365-414 (5 pis.). 



§ Quart. Journ. Micr. Sci., li. (1907) pp. 511-56 (39 figs.). 



