486 



NATURE 



[March 24. 1898 



details of the process, still better work may be done 

 than has yet been accomplished. 



The plan which has been adopted is very simple. The 

 blood vessels of the part to be injected are well washed 

 out with a solution of six parts of common salt in a 

 thousand, parts of water, and the mercury is then injected 

 by inserting into the principal artery a canula connected 

 with a small reservoir of the metal by a piece of rubber 

 tubing. Care must be exercised to prevent the presence 

 of air in the tubing or canula, and the mercury should 

 be injected at a moderately low pressure, which naturally 

 varies in different cases, but as a general rule may be 

 taken at about 30 to 50 mm. of mercury. If the pressure 

 is excessive there is considerable risk that the resistance 



Fig. I. — Arteries of head and brain in a child. 



which the capillaries offer to its advance will be over- 

 come, and the veins will be filled as well as the arteries. 

 One very important detail is that the injected specimen 

 should be moved as little as possible after the injection 

 has been effected, as any shaking or change of position 

 is apt to cause breaks to occur in the column of 

 mercury, and thus to interfere with the success of 

 the skiagraph. 



We have also found that if the specimen has to be 

 kept for some time before the injection is made, one can 

 preserve it very satisfactorily by filling the blood vessels 

 with a 5 per cent, solution of formalin, which in no way 

 interferes with the subsequent injection, except that it 

 lessens somewhat the calibre of the vessels. 



NO. 1482, VOL. 57] 



The skiagraphs have been taken in the ordinary way ; 

 the authors have employed a lo-inch spark " Apps- 

 Newton " coil, and, as a rule, ordinary focus tubes sup- 

 plied by Mr. Newton, which they have found very 

 satisfactory. Of the illustrations which accompany this 

 paper, Fig. i represents the arterial system of the head 

 of a child. The brain is in situ within the cranium, and 

 the whole is injected through the carotid artery in the 

 neck. The very abundant blood supply to the basal 

 ganglionic masses of the brain is well shown, and it is 

 interesting to note the great tortuosity of the internal 

 carotid arteries as they pass through the base of the 

 skull, by which the force of the sudden rise of blood 

 pressure on the advent of the pulse wave is reduced so 

 far as to prevent an undue strain being 

 thrown on the delicate structures within 

 the cranium. In order to prevent the 

 escape of mercury through the several 

 vessels in the neck, the head was placed 

 upside down upon a small beaker, whose 

 shadow appears in the photograph ; 

 where large vessels had been severed, 

 clamp forceps were applied. 



The other illustration (Fig. 2) shows 

 the result of an injection of the branches 

 of the system of the superior vena cava. 

 The subject in this case was a young 

 child, and the incomplete ossification of 

 the bones, especially near the joints, 

 may be incidentally noted. 



In this instance the body was placed 

 lying on its back on the photographic 

 plate, whilst the Rontgen lamp was 

 fixed in front of the chest ; and there- 

 fore the anterior part of the bony 

 skeleton is rendered indistinct, whilst 

 the vertebral column and posterior 

 portions of the ribs are relatively pro- 

 minent. The injection has filled the 

 main branches of the superior caval 

 vein and the spinal veins, and it has 

 penetrated also into the right auricle 

 and ventricle, from which it has reached 

 the larger divisions of the pulmonary 

 artery. 



It must be remembered, in identi- 

 fying the various structures in the 

 photograph, that when a print is taken 

 from a negative the relations of the 

 parts are reversed as in a mirror image, 

 and thus what is really on the right- 

 hand side in the specimen appears on 

 the left in the print, and vice versa. 

 This can, when desired, be obviated 

 either by producing the print by the 

 single transfer carbon process, or by 

 taking the original skiagraph with the 

 film side of the negative furthest from 

 the subject. In this case, since glass 

 considerably obstructs the passage of 

 the X-rays, the negative should be on a celluloid sup- 

 port, and the sensitised surface may be laid upon a 

 fluorescent screen. When this is done, the rays after 

 having penetrated the film are still further utilised by 

 inducing fluorescence of the screen, which in its turn 

 acts on the emulsion of the negative. The result of the 

 manoeuvre, though somewhat shortening the length of 

 exposure, seems to render the resulting impression rather 

 less sharp in its definition. 



A point which must impress any one who looks at 

 these photographs is the extraordinary vascularity of the 

 tissues of the body, and one might reasonably wonder 

 how comparatively small wounds, to say nothing of the 

 large and deep incisions which are required in the course 



