June S, 1883.] 



SCIENCE. 



525 



ec, ectoderm ; ec^, ectoderm of 

 germiniti area; en, entoderm; 

 ds, * deckzellen.' 



a condition wliicli he calls 'relative apnoea.' To ob- 

 tain ' absolute apiioea,' one vagus at least must be 

 intact. Mofeovei', when, by a special apparatus, the 

 central end of the divided vagus was stimulated by 

 a constant current at each artificial inflation, ' abso- 

 lute apnoea' could in must cases be produced ; 

 although in the same animal, without corresponding 

 stimulation of the vagus, only 'relative apnoea' was 

 the result of artificial respiration. That this rhyth- 

 mic stimulation of the vagus is only one of the fac- 

 tors in the production of apnoea is shown by the fact 

 that artificial stimulation alone does not cause apnoea; 

 while, with the vagi cut, artiticial respiration alone will 

 bring about a partial or relative apnoea, indicating a 

 diminished irritability of the respiratory centre. — 

 (H'ienerstteu)i(/s6.,lxxxvi. lii. 101.) w. h. h. [1051 



Mammals, 



Early development of rodents. — In a very 

 important and interesting contribution to this sub- 

 ject, Kupff er describes 

 the following discover- 

 ies from observations 

 of the ova of the field- 

 mouse, made upon sec- 

 tions through the ute- 

 rus and egg in situ. 

 The ovum of Arvicola 

 forms a normal vesi- 

 cle. In the germinal 

 area lie the ectoderm 

 and entoderm in the 

 usual manner. The 

 ectoderm consists, as 

 in rabbits, of a ' deck- 

 schicht' (Ranber, Sitzunr/Kh. naturf. ges. Leipzig, 

 1875) of thin cells, and a main layer of cubical cells, 

 which alone enter into the formation of the embryo. 

 The ' deckschicht' is temporary in the rabbit; but in 

 the field-mouse it is the seat of a rapid and early pro- 

 liferation, which leads to the formation of a knob of 

 cells, which, on the one hand, is attached to the uter- 

 ine-wall, and, on the other, forces in the germinal area, 

 both ectoderm and entoderm. From the germinal 

 area thus invaginated, into the interior of the ovum, 

 the embryo is developed according to the typical 

 method in mammalia. The mass of mesoderm-cells 

 marking the primitive streak, and the position of the 

 future allantois, appear at one end. The amnion 

 folds are developed in front and behind from the 

 inner ectodermal layer, and therefore inside the ' deck- 

 zellen.' The invagination of the germinal area goes so 

 far that the whole egg is elongated in that direction, 

 until it acquires a cylindrical form It is thus evident, 

 that although the ectf)derm occupies, as a result of the 

 Invagination, a central position, yet morphologically it 

 always remains strictly the outside layer. — {Sitzunrisb. 

 akad. wiss. Miinchen, 1882, 621.) c. s. M. [1052 



Embryology of rodents. — Paladino gives the 

 following re.suiue of his results; and, as they have a 

 slight priority of publicatinn over recent German 

 papers (ante 849-851), they deserve especial atten- 

 tion. The whole cylinder formed during the first de- 

 velopmental stages of certain rodents is the embryo, 

 and it is implanted on the decidual new formation 

 by the caudal extremity. This is proved especially by 

 the fact that it is this part from which the allantois 

 arises. The cylinder, and the vascular portion of the 

 decidual new fortnation, are continuous, and so remain 

 throughout gestation by means of the vessels falsely 

 called oraphaloid. The decidua forms not only the 

 placenta, but also the first envelope around the em- 

 ijryo, — the chorion, falsely so called. (This is in 



direct contradiction to the latest opinions of Hensen. ) 

 Between the embryo and the decidua is a large space, 

 filled at first with blood, which Paladino thinks is 

 probably produced by the metamorphosis of the 

 granulosa cells discharged from the Graafian follicle 

 along with the ovum ( !). — (Arch. ital. bioL, ii. 36.3. ) 

 c. s. M. [1053 



Germinal layers not homologous. — EepiachofE, 

 whose singular hypothesis concerning themammalian 

 ovum was reported (627), has advanced the still more 

 remarkable opinion that the germinal layers in ver- 

 tebrates are not homologous primitive organs, and 

 maintains that the same organ may arise in different 

 animals from different layers. (This is directly op- 

 posed, especially as regards the notochord and the 

 mesoderm, to which Keijiachoff refers as illustrations, 

 by the best recent investigations, and, indeed, the 

 whole theory seems to the reporter without foun- 

 dation.) —(ZooZ. anz., vi. 148.) c. s. M. [1054 



ANTHROPOLOGY. 



Tylor's lecture at Oxford. — On Feb. 15 and 

 21, Prof. E. B. Tylor lectured at the University mu- 

 seum, Oxford, upon anthropology. The occasion 

 was the instalment of a museum of civilization, the 

 nucleus of which is the Pitt-Rivers collection, previ- 

 ously mentioned in Science. The speaker first drew 

 attention to the fact that the theory of development 

 has had its own evolution parallel with the progress 

 of knowledge. Pritchard recognized the descent of 

 mankind from one pair, whom he considered to have 

 been negroes; and as we have been able to recon- 

 struct the ancestry of the horse, Huxley leads us to 

 hope that we may some day discover the fossil pedi- 

 gree of his rider. 



Mr. Tylor next spoke of the approach which crani- 

 oscopy is making to an exact science, drawing his 

 illustrations from the crania of the British barrows, 

 and other localities of undisturbed population. Com- 

 parative philology, properly understood, may tell its 

 story in perfect accordance with anatomy. The 

 blended parentage of the Fijians is heard in their 

 speech, as it is seen in their faces. The cross-section 

 of a single hair, examined microscopically by Pruner's 

 method, shows it circular, or oval, or reniform; its 

 follicle curvature may be estimated by the average 

 diameter of the curls, as proposed by Moseley ; its col- 

 oring-matter may be estimated by Sorby's method. 

 This examination enables one to judge in what divis- 

 ion of the human species to classify its owner. Cli- 

 mate, albinism, ' Addison's disease,' and other 

 natural causes in their relation to race-color, are 

 carefully considered. 



It is upon the evolution of civilization, however, 

 that Mr. Tylor is most happy, a subject to which he 

 has devoted the most of his life. The last portion of 

 the addresses, therefore, is devoted to the unfolding 

 of several phases of social life in their relation to race 

 and history. — [Nature, May 3.) [1055 



The Trenton gravels. — Dr. C. C. Abbott has 

 been observing closely the removal of gravel from 

 the drifts of the Delaware near Trenton by railroad 

 excavations, and has discovered new evidences of 

 the existence of paleolithic man. The removal of the 

 material reveals the fact that the beds were de- 

 posited at different times, masses of bowlders being 

 overlaid by masses of sand, one of which, averaging 

 a foot in depth, and extending nearly three himdred 

 yards along the exposure, yielded not only the typi- 

 cal paleolithic implement, but four chipped stones 

 of less definite shape, all of argiUite. These objects 

 were overcapped by a deposit nearly seven feet in 



