472 



KNOWLEDGE & SCIENTIFIC NEWS. 



[July, 1906. 



its floral surrounding-s. The rolled-up leaf, adjacent to 

 the birch leaf in the fourth illustration of this series, is 

 the chosen home of a beetle. Its twig-like companion 

 is none other than the larva of a Thorn Moth 

 (S. illumaria). 



The advantages of the three-colour process of photo- 

 graphv were also apparent in Mr. W. Saville-Kent's 

 brightly illuminated transparencies illustrating the 

 fauna of the Polynesian coral reefs, especially those re- 

 ferring to the gaily coloured fishes which make the 

 recesses of such coral growths their habitation. A 

 striking series of specimens of fossil plants from the 

 English coal measures, with illustrative microscopical 

 slides, was on view, a display with which Miss M. Ben- 

 son, Miss W. Brenchley, Prof. F. Oliver, F.R.S., and 

 others were identified. A newly discovered petrified 

 stem from Shore, Lancashire, indicated the structure 

 to be of a type hitherto unknown. Some models of 

 branching stems, w-hich furnished accurate reconstruc- 

 tions of petrifications, \\ere, too, of great interest. 



Sir William Crookes conducted an elaborate series of 

 experiments in illustration of some properties of the 

 diamond. The squeezing of a natural crystal into steel 

 by means of hydraulic pressure in order to demonstrate 

 the hardness of diamond was beautifully shown by the 

 optical projection upon a screen of the slow transit of 

 the object into the metal until it became lost to sight. 

 In the electric arc the precious gem was seen burning 

 up and turning into graphite. The facile manner in 

 which it will plane a glass surface was shown by a slide 

 of curh' glass shavings. One diamond thrown upon 

 the screen had been obtained from the remarkable 

 Canyon Diablo meteorite, of Arizona. Prof. W. Gow- 

 land also showed under the microscope diamonds found 

 in this meteorite. Some will, perhaps, remember that 

 it was this particular meteoric mass that secured the 

 ubiquitous attentions of American speculators a year 

 or so ago, when the inevitable company was formed, 

 with the idea — of course a futile one, of exploiting it 

 for diamonds. 



From the Royal Institution laboratory came Sir 

 James Dewar's new charcoal calorimeter and thermo- 

 scope. In this instrument charcoal when utilised at 

 the temperature of liquid hydrogen and in conjunction 

 with certain gases exhibits great sensibility to heat and 

 light radiation, and can be used in calorimetry. There 

 were also spectrum tubes containing helium, neon, 

 krypton, and xenon, these gases having been separated 

 by the charcoal method. A demonstration of the 

 scientific uses of liquid air formed a popular feature. 

 The fine piece of photo-micrographic apparatus for ultra- 

 violet light, designed by Dr. Kohler, and ably ex- 

 plained by Mr. ^lax Poser, of the firm of Zeiss, was 

 considered by physicists present to be a splendid instru- 

 mental achievement. It was suitably shown for the 

 first time in this country at the soiree. 



In archaeology. Dr. Flinders Petrie contributed ex- 

 amples of black incised pottery from Egypt, of date 

 2000 B.C., as well as photographs from Sinai taken 

 during the progress of his recent exploring ex- 

 pedition in that quarter. 



Lastly, we should not omit to mention a set of 

 diagrams sent by Prof. Karl Pearson, F.R.S., and 

 Mr. J. Blakeman, illustrative of Lord Ravleigh's solu- 

 tion of the "problem of the Random Walk," a 

 mathematical excursion, decidedly perplexing, how- 

 ever, to the layman. For information on the subject, 

 our readers should refer to Nature, Vol. 72. 



Some Rudimentary 

 Structures. 



By R. LVDEKKER. 



On a first visit to an English assize court, the stranger, 

 if he occupy a sufficiently elevated position, will 

 scarcely fail to notice the presence of a small black 

 patch on the top of the full-bottomed wig of the pre- 

 siding judge, and, if he be of an inquiring disposition, 

 he will want to know the reason for this apparently 

 useless feature. Reference to any treatise on the his- 

 tory of costume will inform him that this apparently 

 unmeaning patch is the last remnant or survival of the 

 coif, or black cap, with pendent lappets, originally 

 worn by the " sergeants learned in the law," from 

 among which bod}- the judges were formerly selected. 

 The patch affords therefore an excellent example of a 

 structure which, although now perfectly useless, once 

 had a definite and more or less important function. In 

 other words, it exactly corresponds to what are com- 

 monly called rudimentary structures in the animal 

 kingdom. I say commonly called rudimentary struc- 

 tures, purposely, because in scientific circles they are 

 now more generally designated vestigiary structures; 

 and, strictly speaking, quite rightly so, for a rudiment 

 properly means the commencement of any thing, 

 whereas these are the last vestiges of the structures 

 they represent. They are decadent, and not incipient. 

 Nevertheless, since the term vestigiary is somewhat 

 cumbrous, and by no means so well known as rudi- 

 mentary, I shall take leave to use the latter, especially 

 as it is employed by Darwin, in this sense, in the 

 " Origin of Species." 



Rudimentary, or more or less completely functionless 

 organs are extremely common in both the animal and 

 the vegetable kingdoms; and they can have but one 

 meaning. That is to say, they afford practically de- 

 cisive and irrefutable evidence in the minds of all 

 unprejudiced persons of the truth of the doctrine of 

 evolution. For it is absolutely inconcei\ able that such 

 useless structures, which in many instances can be 

 traced by regular gradations into those whi-h were 

 evidently functional, could have been created in their 

 present condition. Indeed, if we had no other evi- 

 dence in favour of the evolution cf animal forms from 

 pre-existing types, it is perhaps not too much to say 

 that the evidence of these rudimentary structures would 

 alone be sufficient to prove the truth of that great doctrine. 



.Since rudimentary structures are so common in 

 nature we suffer from an embarras du richesses in at- 

 tempting to select instances to form the subject of an 

 article of the length favoured by the Editor of this 

 journal; and the reader must consequently be not sur- 

 prised if he finds no mention of many cases of this 

 kind with which he may be more or less familiar. As a 

 matter of fact, cases of this nature to which the present 

 writer has had occasion to devote special attention form 

 the chief of those noticed in this article. 



Among the larger animals of the present dav, no 

 species is more highly specialised than the horse (and 

 its immediate relatives), and it would consequently be 

 only reasonable to expect that in the course of its 

 evolutionary progress this creature should have found 

 certain elements in its organisation superfluous, and 

 should therefore have done its best to discard them. 

 This expectation is fully realised by the actual state of 



