NATURE 



{Dec. 13, 1888 



cells forbids the assumption of a secondary junction ; in 

 our case the junction of fibres of the 17th spinal nerve 

 with those fibres of the old muscle which, by migration or 

 by increase in number, have come to be situated on the 

 17 th metamere. 



Fuerbringer explains these changes by an ingenious 

 hypothesis, viz. by a peculiar mode of growth, which he 

 terms "growth by metameric opposition or reduction of 

 the muscles and nerves." The primordial extremity was 

 perhaps somewhat broader, and extended over a greater 

 number of metameres. This surplus of locomotory 

 elements was reduced by the following concentration of 

 the limb, but not so completely that those metameres did 

 not in later generations retain vi inertice the faculty of re- 

 producing some of the nearly lost elements in a primitive 

 condition. The reduction of these germs, that are not 

 called upon, would become complete, they would be lost, 

 but for the particular stimulus which they and their meta- 

 meres receive from the extremity. The real nature of the 

 interdependence between a stimulus and its effect is still 

 an obscure problem ; but we can imagine that the shifting 

 limb exercised a stimulating influence upon the newly 

 overlaid metameres, and that this stimulus awakened the 

 latent nerve-muscle germs, which then joined the already 

 existing apparatus of the approaching limb. Such latent 

 germs, when once started into activity, may well be re- 

 quired to fully develop in order to make up for the reduc- 

 tion of the motory elements at the opposite end o(4be 

 limb. As a support for this speculation, Fuerbringer 

 alludes to the fact that the anterior limb of birds now 

 tends to shift backwards, and it is the last root of the 

 brachial plexus which contains relatively the greatest 

 number of those immeasurably fine elements that he 

 is inclined to consider as latent germs. The absolutely 

 gradual mode of growth, which this metameric apparition 

 postulates, makes it less perplexing that parts which are 

 only parhomologous should be the very counterfeij^ of 

 each other. ' 



Pp. 984-91. What has caused the backward shifting 

 of the anterior extremity ? To inquire into the causation 

 of the length of the neck means the same problem in a 

 different form. A correlation between the length of the 

 neck and that of the legs is not always there, e.g. swans. 

 The assumption of intercalation of vertebra; is still un- 

 justifiable, being quite unsupported by proofs. There 

 remain lengthening of the single vertebra; and the shifting 

 of the extremity along the axis. 



In stretching our neck, we bring into play chiefly two 

 sets of muscles, viz. the extensors of the neck and the 

 depressors of the shoulder and anterior limb. There is 

 no reason for assuming that the ancestors of recent birds 

 did not effect the stretching of their necks in the same 

 way. Continued habit results in permanent conditions. 

 In a well-extended neck the vertebra; are in more perfect 

 equilibrium and in conditions more favourable to their 

 nutrition and growth than if the neck were much curved 

 and doubled up. The pectoral girdle, the sternum, and 

 the whole anterior limb of birds are in toto retracted by 

 the incessant pulling of the mm. rhomboides, serrati, 

 latissimus dorsi, and the abdominal muscles, the latter so 

 far as they are attached to the sternum. Many of the 

 thoracic muscles show a pronounced tendency to extend 

 their origin tailwards. As a rule, large birds possess 

 more cervical vertebrae than smaller birds, and they are 

 noteworthy for their soaring and more lasting mode of 

 flight. During the time that the wings are not moved, 

 but are kept in a spread-out position, they offer a greater 

 resistance to the air than the far smaller but heavier bulk 

 of the body. The momentum gained by the body will there- 

 fore tend to move the latter forwards with more velocity 

 than the resisting wings. In other words, the wings will 

 remain behind the body, and the strain produced by this 

 difference in equilibrium will act upon the ribs, since 

 these form the weakest connection of the sternum -f 



shoulder-girdle + wing with the rest of the body. The 

 anterior thoracic ribs will lose their sterno-costal charac- 

 ter, and be transformed into cervical ribs, i.e. the neck is 

 lengthened, and the whole pectoral girdle, with the whole 

 apparatus of flight, will be shifted backwards. The 

 reduction of thoracic into cervical ribs can be proved on 

 grounds independent of this question. The long necks 

 of the Ratite birds seem to offer a serious objection 

 to the view just explained, but Fuerbringer pleads in 

 another part of his work (p. 1 504) for their being descend- 

 ants of birds which possessed well-developed power of 

 flight. 



Pp. 991-95 contain some remarkable observations about 

 the size of birds. On the whole, small birds show more 

 primitive and simpler conditions of structure, whilst the 

 larger members of the same group exhibit a more one- 

 sided development, and consequently greater deviation 

 from the common stock. The first birds were probably 

 smaller than Archa;opteryx. Reptiles and mammals show 

 likewise in their earlier and smaller types more primitive 

 features than do their larger descendants. It is there- 

 fore the study of the smaller members within given groups 

 of animals which promises the best results as to their 

 phylogeny. H. Gadow. 



{To be continued.) 



STATISTICS OF THE BRITISH 

 ASSOCIATION. 



T T may prove instructive to see, in diagram-form, some 

 ■*• statistics connected with the history of the British 

 Association. We go back only to 1850 (the Association, 

 it is known, dates from 1831), and our curves relate to 

 the total attendance in each year to the present, to 

 attendance of ladies, and to grants in aid of scientific 

 research. 



As regards attendance, it will be seen that the 

 maximum is that of the Manchester meeting in 1887, 

 the figure 3838 having been then reached. Newcastle, 

 in 1863, comes next, with 3335; then Manchester again, 

 in 1 86 1, with 3133. The curve reaches high points also 

 in the case of Liverpool in 1870, Glasgow in 1876, 

 Southport in 1883, &c. 



On the other, hand, we find the curve reaching its 

 lowest, in this period, at Ipswich, in 1851, with 710 ; 

 while Hull, in 1853, Swansea in 1880, Cheltenham in 

 1856, Cambridge in 1862, and Plymouth in 1877, 

 furnish other low points, in rising series. 



The general course of the curve seems to be that of 

 rise to a maximum at Newcastle in 1863, then descent to 

 Swansea in 1880, followed by another rise to the peak 

 representing Manchester in 1887. The meeting at Mon- 

 treal (in 1884) it will be seen, takes a fairly good position 

 as to numbers (1777). 



Several places had a second visit in the period con- 

 sidered (not necessarily second in the whole series) ; these 

 are indicated by figures after the abbreviated names. 

 How do those repeated visits compare with the earlier ? 

 In general, the second visit considerably exceeds the 

 first in numbers. But in the case of Aberdeen the 

 second figure (2203) is less than the first (2564) ; and 

 the same holds for Bath, 1950 this year, as against 

 2802 in 1864. The former Bath meeting had no doubt 

 exceptional attractions in the visit of Livingstone, &c. 

 The earlier Aberdeen meeting was presided over by the 

 Prince Consort. 



Of the total number, something like one-half are 

 usually associates for the year (paying ^i), the others 

 annual or life members, ladies, and foreigners. These 

 groups do not call for special remark here ; but we have 

 given a curve of ladies' attendance, as there is room for 

 it, and it is somewhat curious. It seems to have a 



