6 4 



SCIENCE-GOSSIP. 



the Undercliff at Niton, and which have been 

 shown by Dr. G. J. Hinde to consist entirely of 

 sponge remains, are the most noticeable feature 

 of the Upper Greensand, although less striking 

 beds of similar origin occur about the same horizon 

 at other places on the mainland. Below the Chert 

 Beds is the Malm Rock, containing beds of freestone 

 much used locally for building. The following 

 thicknesses are given, and good exposures may be 

 seen at each place named. 



Coinpton Bay Gore Cliff Culver Cliff 

 Chert Beds . . 13 feet 27 feet | „ f 



Malm Rock . . 73 feet 94 feet J 



The fallen material of the Undercliff consists 

 almost entirely of Upper Greensand ; the Gault, 

 except at Blackgang, is entirely concealed by it. 

 At Culver Cliff beds of chert occur, but the 

 passage from the Upper Greensand to the Chalk is 

 there so complete that it is difficult to define the 

 exact limits of the different beds as seen in the 



southern downs. Exogyra conica, Inoccramus latus, 

 Pectcn asper, Plicatula pectinoidcs, Ammonites rostratus, 

 and Am. varians are the more typical fossils of the 

 Isle of Wight Upper Greensand. 



Immediately above the Chert Beds follows the 

 highly fossiliferous Chloritic Marl, by some writers 

 classed with the Upper Greensand, and by others 

 with the Chalk. It is of no great thickness, varying 

 from fifteen feet at Culver Cliff, where it is difficult 

 to recognize, to seven feet at Gore Cliff, where it is 

 very distinct. At the latter place it is simply 

 crowded with fossils, easily collected in perfect 

 condition. The more common are sponges : 

 Avicula gyphaoides, Exogyra conica, Inoceramns, 

 latus, Pecten asper, Plicatula pectinoides, Pleurotomaria 

 Moreausiana, P. Rhodani, Solarium ornatum, Turbo, 

 Ammonites Coupei, Am. curvatus, Am. Mantelli, Am. 

 varians (many forms), Nautilus, Turrilites Bcrgeri, 

 and Tu. Morrisii. 



(To be concluded next month.) 



WHITENING OF HAIRS AND FEATHERS. 



By John R. Lord and H. Meade-Briggs. 



T\/TY friend Mr. K. Hurlstone Jones's paper on 

 "Pseudo-albino Sparrows" seems to have 

 excited considerable interest, and it is in the hope 

 that I might be able to throw some more light on 

 the subject that I write this. The exact anatomy 

 and physiology on the condition would be difficult 

 to state, and there is no doubt that more observa- 

 tions will have to be made before a definite 

 announcement can be made. I have carefully 

 followed the structure and uses of both hairs and 

 feathers, and seeing that one is the homologue of 

 the other, I am of the opinion that the whitening 

 of the hair and the disappearance of colour from 

 feathers are homologous conditions. It would 

 seem then that the causes which act in one may 

 act in the other. 



Of one thing there is no doubt : there is no cir- 

 culation of blood in a feather (see Science-Gossip, 

 O.S., 1893, page 54). We must therefore look else- 

 where for our explanation. If we were to accept 

 Mandl'sidea as to the growth of hair, the disappear- 

 ance of pigment would be easily explained ; but since 

 the hair grows at its root and not near its tip that 

 theory falls to the ground. I am not convinced 

 that heredity, in the sense of a relapse to a 

 former condition, is the main cause in birds, and I 

 am less convinced that the same holds good in 

 mammals. In the first place I will take hairs. A 

 hairy coat may whiten as a result of a normal or 

 abnormal cause. At certain times of the year the 

 hairs may be cast and a new coat of white hairs 

 formed, i.e. hairs with less or without pigment. 

 As a result of deficient nutrition or of lower 



vitality normal in old age, the hairs may be cast or 

 continue to grow, but with a gradually diminishing 

 amount of pigment in them. The hair may be 

 bleached by long-continued exposure. In this 

 case the tips of the hairs are first affected. These 

 are some examples of a normal modification. A 

 normal cause may become abnormal if the time at 

 which it produces its effects is wrong. Again, any 

 condition which deranges the trophic centres may 

 affect the production of hair, such as overwork, 

 mental anxiety, various diseases and neurotic 

 conditions. 



People are very fond of finding and dilating on 

 the marvellous, and too much stress is certainly 

 laid on a few isolated cases of the hair suddenly 

 turning white which have been recorded. Even 

 these cases have much doubt about them, and are 

 so scarce that they hardly merit consideration. It 

 is so common in fiction that the public will barely 

 tolerate the idea that there are only a very few 

 cases on record that have any reliable foundation. 



Let us now look at the condition in birds. Is it 

 not possible to think that there are similar causes 

 here ? Feathers are not dead structures, but bear 

 nearly throughout them, a network of living cells 

 quite capable of absorbing or of producing melanin 

 pigment. Of course there are no trophic nerves 

 in the feather, but there are in the vascular 

 papilla, and there is abundant evidence elsewhere 

 to show that probably all living cells are to a 

 certain extent under the control of the nervous 

 system. It is not necessary that a nerve should 

 be closely related to a cell to modify its action. 



