516 



SCIENCE. 



[N. S. Vol. III. No. 66, 



districts ' as afTected by their animal inliabit- 

 ants; miue to tlie aggregations of animals accord- 

 ing to their habitats. 



The - differences are counterbalanced by the 

 resemblances in other respects. Let me close 

 then by endorsing the 'favorable criticism of 

 Dr. Ortmann's work by Dr. Baur and commend- 

 ing it as well worthy of attention. 



■ ' Theo. Gill. 



rontgen eay expebiments. 



EXPEKIMENTS with Rontgen Rays have been 

 carried on very persistently at Case School of 

 Applied Science for several weeks, and some 

 very interesting results have been obtained. 

 The main object has been to secure good photo- 

 graphs of the human skeleton in a living sub- 

 ject, and to increase the practical efficiency of 

 the apparatus. The accompanying photographs 

 of the bones of the hand and forearm, and of an 

 aluminium medal, will indicate the degree of 

 success obtained. 



The arm was photographed with an exposure 

 of twenty minutes, while the medal {^-^ inch 

 thick) required but five minutes. The Crookes 

 tube used is of the well-known spherical form, 

 having four electrodes, designed to show that 

 the discharge in a high vacuum is independent of 

 the anode, and is one of a set which was ex- 

 hibited at the World's Fair. It was excited by 

 an induction coil giving about a six-inch spark 

 in air, when using a current of three amperes 

 and twenty volts, obtained from eleven cells of 

 storage battery. The arm was held by band- 

 ages to the plateholder, which was supported 

 in an inclined position upon a special stand. 

 The usual plateholder slide of hard pasteboard 

 was between the hand and plate. The tube 

 was placed at a distance of twelve inches above 

 the wrist. Rapid plates were used and devel- 

 oped in the usual way with eikonogen and 

 hydrochinon developer. Slow lantern slide 

 plates give nearly as good results, indicating 

 that the sensitiveness of the plate to ordinary 

 light is no criterion in this work. A great deal 

 of detail appears plainly during development 

 which disappears in the ' fixing ' process. Vari- 

 ous kinds of developers and fixing agents have 

 been tried to overcome this, without success. 



A photograph showing the bones of the fingers 



has been made with ten seconds' exposure, the 

 tube being two inches above the plate. The 

 bones of the entire arm, including the shoulder 

 joint and of the foot, have been satisfactorily 

 photographed. Attempts have been made to 

 photograph the chest and head with exposures 

 of one hour in each case, the tube being eigh- 

 teen inches from the plate. The resulting nega- 

 tives show a surprising amount of detail, which 

 is too faint for satisfactory reproduction. The 

 chest picture shows eight ribs on each side of 

 the spinal column, a dark streak in the latter 

 corresponding to the spinal cord. Under the 

 region of the heart the ribs do not show, indica- 

 ting that the heart is more opaque than the lung 

 tissue. The collar bone is prominent, while the 

 details of the shoulder joint can be seen. The 

 picture of the head shows the following details : 

 The spinal column in the neck, the jaw bones, 

 with teeth and spaces where several are missing, 

 the nasal cavities, the thickening of the bone 

 showing clearly the outline of the ear, the thin 

 places at the temples, the floor of the brain 

 cavity and the ragged edge where bone and 

 cartilage join in the nose. These pictures, 

 though of little surgical value, are very interest- 

 ing experimentally. Some of the negatives made 

 clearly show the ligaments connecting the bones 

 at the joints, while none have so far shown any 

 blood vessels or nerves. 



Bullets have been located in the hands of four 

 men, and numerous cases of hands injured by 

 machinery and of deformities have been ex- 

 amined, the exposures varying from two to 

 twenty minutes. Some very interesting and 

 valuable pictures of diseased arm bones and of 

 fractures of the arm have been taken. In one 

 case four inches of the arm bone had been re 

 moved five years ago, and the extent of the dis- 

 ease is clearly shown. Views of the ii-actures 

 where the ends of the bones are not in apposi- 

 tion are of value to the surgeons. These pho- 

 tographs are taken through bandages, splints 

 and silicate of sodium casts without hindrance. 



A most interesting study has been the position 

 of the various small bones of the wrist in differ- 

 ent positions of the hand. 



Many interesting points are noted in the work, 

 which are suggestive in a theoretical way, de- 

 tails of which are not ready for publication. 



