6 



KNOWLEDGE. 



[January 1, 1901. 



smaller ulnar eraiuence. The radial emineuoe is, how- 

 ever, divided into two portions by a deep groove, and 

 on all five eminences are observable the usual 

 papillary ridges and gi-ooves traversed by the afore- 

 said irregulai" network of grooves. On the 

 palmar aspect of the second joint of the Angel's, and on 

 such portion of the centre of the palm as exhibits an 

 impression, the papillai'y, ridges, instead of being uni- 

 formly distributed in regi-ilar lines, ai'e restricted to 

 certain small pustule-like eminences, on which, however, 

 the linear arrangement is distinctly visible with the aid 

 of a lens. And if it had been possible to obtain an 

 impression of the basal joints of the fingers, a similar 

 pattern would doubtless have been noticeable there also. 

 Whether the curious arrangement of canals characteristic 

 of the palm of the red-fronted lemur, or a modification 

 thereof, obtains in all the true lemui's, must await the 

 acquisition of additional fi-esh specimens of the hand; 

 but in that species at all events it seems certain that 

 these pads must have a kind of sucker-like action, which 

 greatly increases the firmness of their owner's hold 

 on the boughs it grasps. 



Apparently this type of palm-structure culminates 

 in the curious little tarsier of the Malay Islands, in 

 which the long and slender toes terminate in round 

 sucker-like disks; similar disks occiu'ring on the toes 

 of the hind-foot. Unfortunately I have had no oppor- 

 tunity of taking the palm-impression of a recently 

 deceased tarsier, and it will probably be long before 

 such a chance occurs, so that I can say nothing as to 

 the mode of arrangement of the papillary ridges. 



It may be added that the finger and toe-pads of 

 tliose curious lizards commonly known as geckos eve 

 likewise modified into adhesive disks. But in this case 

 the sucking action is caused by the skin being raised 

 into a series of parallel plates, and as palmar eminences, 

 as well as papillary ridges, are wanting, the stiiicture is 

 not apparently strictly comparable with what obtains 

 in the tarsier and the lemurs. 



But even the foregoing by no means exhausts the 

 subject of palmar and plantar eminences. Anyone of 

 my readers who takes the trouble to examine the feet 

 of a cat. a dog, or a rabbit will find a number of bare 

 elevated pads, covered with rough granular skin, inter- 

 spersed among the generally haii-y surface. In all cases, 

 both in the fore and hind limb, one of these bare pads 

 will be found occupying the lower surface of the terminal 

 joint of each toe, lying immediately below the claw. 

 And it will be quite obvious that these correspond to 

 the pattern-bearing eminences occupying the balls of 

 the thumb and fingers of the monkey. In regard to 

 the pads on the palm and sole, these are subject to some 

 degree of variation in the carnivora, and they may 

 sometimes coalesce to such a degree that their original 

 relations are more or less obscured. But in some of these 

 animals* three distinct pads are obsei-vable in the fore- 

 foot corresponding in position with the interdigital 

 eminences of the monkey's palm. Continuing the semi- 

 circle formed by these three is a fourth pad, repre- 

 senting the radial eminence of the monkey, while further 

 down on the palm is one corresponding to the ulnai- 

 eminence of the latter; a small additional pad being 

 irtercalated between the radial and ulnar. 



It is thus fully demonstrated that the pads on the 

 fore-foot of the dog and the cat con-espond with the 



* Those who are interested in the subject may turn to the figure of 

 the foot-pads of the hn.mng, giren by the late' Professor MiTart on 

 page 158 of the Proceedings of the Zo^Io^nial Societv for the Tear 

 1882. • ' 



pattern-bearing eminences of the monkey's palm, and 

 these again with the much less distinctly defined 

 eminences on the human hand. In animals. which use 

 both feet exclusively for walking, it will, however, be 

 obvious that delicate papillary ridges, designed pai'tly 

 for the purpose of obtaining a firm grip of any object 

 seized, and paitly to act as organs of touch, would be 

 perfectly useless. And we accordingly find the papillaiy 

 ridges of man and monkeys rej^laced in the cat, the dog, 

 and the rabbit by granular conical elevations, which 

 have, however, doubtless the same structure, and which 

 are foreshadowed by the pustules on the finger and palm 

 of the lemvtrs. 



One other point remains to be mentioned. In all the 

 lower monkeys that have been examined both by Dr. 

 Hepburn and myself the pattern of the papillaiy ridges 

 is of the concentric type (as shown in Fig. 1), in which 

 the central ridges are longitudinal and the external 

 ones form broad ellipses. In the chimpanzee, however, 

 and probably also in some or all of the other man-like 

 apes, the pattern on the balls of the fingers is of the 

 form known as the looped type, which is of common 

 occuiTence in the fingers of the human hand. On the 

 finger-tips of man alone occiars the still more complicated 

 whorled type. The explanation of the characters of 

 these two latter types may be reserved for an article 

 devoted to human finger-prints ; and it will accordingly 

 sufiice on this occasion to record the fact that even in 

 such a minute detail as the aiTangement of the lines 

 on the fingers of the man-like apes and man stand apart 

 from their kindred, and that in man alone is the most 

 complicated type ever developed, although even in him 

 it is comparatively rare. 



PHOTOGRAPHY "IN NATURAL COLOURS," 

 BY THE MCDONOUGH-JOLY PROCESS. 



By H. Snowden Ward, f.k.p.s., Editor of The Photogram. 



In the present state of scientific knowledge, and in 

 writing for the readers of Knowledge itself, it is un- 

 necessary to say anything about the general history of 

 attempts to solve the problem of " photogi-aphy in tho 

 colours of nature." It may be well, however, to briefly 

 outline tlie history of the process now known as the 

 McDoiiough-Joly, and perhaps, even before beginning 

 the history, to explain why I write of an old process at 

 this particular time. The reason is that this process 

 has only just reached the point of thorough practical 

 bility, and that in a few months it ought to be possible 

 for every photographer to obtain, at a very small cost, 

 the necessary apparatus and materials. 



I have no brief on behalf of this particular process, 

 and I realise the great beauty and value — if you will, 

 the superior beauty and value — of the resnlts of tJie 

 triple-film supeqaosition process. The two methods 

 supplement rather than antagonise each other, and each 

 has its advantages. Those claimed for the McDonough- 

 Joly process are Wiat it requires the smallest possible 

 alteration of existing apparatus, no change in existing 

 methods, and necessitates only one exposure, with one 

 lens, on one plate, to secure the triple colour-record. 

 Fm-ther, from the negative so made, a single trans- 

 pai'ency can be prepared (in the same way as making 

 an ordinai-y lantern-slide) for lantern projection, and a 

 single piinting by well-known processes will give a 

 colour-print on paper. To project the transparency in 

 coloiu'K, a coloui'-acrccn is necessary, and to make the 

 print in colour it is necessary that the photographic 

 sensitive surface shall have been laid by the manufac- 



