PHYSIOLOGY, RECENT. 



753 



ready been made, seem to indicate that this is 

 not the case." 



M. Ranvier has been much assisted in his 

 investigations of the structure of the organs of 

 touch by the examination of the structure of 

 infants. At birth, the nerves of touch may be 

 found to pass into certain papillae on the palmar 

 aspect of the fingers, immediately beneath the 

 cells of the mucous layer of Malpighi, where 

 they form a net-work of ramifications which, 

 though distinct, are closely pressed together. 

 No cellular elements are at this time mixed 

 with the net-work, but a small collection of 

 round cells exists beneath it. These gradually 

 surround the net-work and pass in among its 

 branches ; the whole soon becomes united, 

 and a tactile corpuscle is formed. Sometimes 

 the corpuscle remains unilobar, bat more fre- 

 quently other lobes are formed in the same 

 manner as the first one, and joined to it. Hence 

 it is that, in young children, the nerve-fibers 

 which enter into the composition of the tactile 

 corpuscles are separated by layers of cells, 

 which, in the course of development, become 

 pushed to the periphery of each lobe, and the 

 most of them undergo a considerable atrophy. 

 This fact suggests that they are not nervous in 

 their nature, for the nerve-cells, so far from 

 undergoing atrophy during growth, gradually 

 increase in size to their full development. M. 

 Ranvier has not perceived any communication 

 between the nerve-fibers and the cells in the 

 tactile corpuscle ; the ramifying branches of the 

 nerve-fibers, after a tortuous and usually com- 

 plicated course, end in free, flattened knobs. 



Wolff has examined the mode in which 

 nerves terminate in muscle, and has arrived at 

 the conclusion that the Doyerian eminences, or 

 end-plates, are artificial products. The neu- 

 rilemma of the nerve passes continuously, ho 

 believes, into the sarcolemma of the muscle, 

 and the axis cylinder into the muscle-sub- 

 stance. 



The duration of muscular contraction in 

 different muscles of the same animal and in 

 different animals has been made the subject of 

 experiment by Dr. Cash, who has found, in 

 agreement with Weber's previous observations, 

 that some muscles contract under the same 

 stimulus much more rapidly than others, and 

 that temperature exerts a remarkable influ- 

 ence, a diminution of temperature greatly pro- 

 tracting the duration of the two phases of 

 pulsation. He has also shown that the form 

 of the curve presented by each muscle differs 

 from that of others; and that in many in- 

 stances the tracing is so constant and peculiar 

 as to serve readily to indicate the muscle from 

 which it is derived. 



Professor 0. M. Woodward, of Washington 

 University, St. Louis, Missouri, has devoted a 

 chapter of hi.s work on the St. Louis Bridge to 

 the review of the affections which the men era- 

 ployed in sinking the piers for the structure suf- 

 fered from compressed air, and of the theories 

 that were proposed to account for the trouble. 

 VOL. xxi. 48 A 



No serious drawback was perceived to working 

 lor four or even six hours consecutively in the 

 air-chamber, till the cutting-edge of the cai>-i>n 

 of the east pier was nearly sixty feet below the 

 surface of the river. From that time on it 

 was found best gradually to shorten the work- 

 ing-time and make the rests longer, till the 5th 

 of February, when a depth of sixty-five feet had 

 been reached, and the work-time was made 

 three watches of two hours each, with two- 

 hour rests. The first effect noticed upon the 

 men was a muscular paralysis of the lower 

 limbs, without pain, which would pass off in 

 a day or two, but which became more difficult 

 to subdue, more extended and painful, as the 

 caisson was sunk deeper. It was regarded as 

 a subject for joking at first, but grew more 

 serious by the middle of February, after which, 

 the depth being seventy-six feet, severe cases be- 

 came more frequent. The superintendent of the 

 work noticed the fact that the sick men were 

 often thinly clad and poorly fed. At the end 

 of March, several persons having died within a 

 few days shortly after coming out of the excava- 

 tions, Dr. A. Jaminet was appointed to take 

 medical charge of the men and establish suit- 

 able regulations for their well-being. He had 

 been a frequent visitor to the air-chamber, had 

 noticed the men as they came out, and had 

 observed that their appearance was pallid and 

 cold, that in some the pulse was quick but 

 somewhat weak, while with others it was M 

 low as sixty ; that without exception the work- 

 men complained of fatigue; that the pulse 

 always quickened on entering the air-chamber, 

 though it soon fell to the normal rate, and even 

 lower; that the number of respirations in- 

 creased, and a feeling of exhilaration came on 

 in the air-chamber; and that the workmen 

 sweated profusely during their stay in it, al- 

 though the temperature was often below 60 

 Fahr. The air-lock was, as a rule, excessively 

 warm when the pressure was increasing, and 

 excessively cold when the pressure was dimin- 

 ishing. On the day the caisson touched the 

 rock, when the pressure was forty pounds above 

 the normal, Dr. Jaminet was conscious of a great 

 loss of heat and a violent pain in his head, while 

 in the air-lock on his way out, and afterward 

 became partially paralyzed. Among six hun- 

 dred men employed, one hundred and nine- 

 teen cases important enough to need med- 

 ical treatment were reported at both piers, 

 fourteen of which died and two were crippled. 

 Pott-martem examinations were held in the case 

 of eight. I>r. Clark, of tho City Hospital in 

 St. Louis, believed that the congestion observed 

 was caus.-il by the forcing of the blood in upon 

 the interior organs of the body in consequence 

 of the increased atmospheric pressure. Another 

 physician thought the men were poisoned by 

 carbonic acid which had been abnormally re- 

 tained within the system while in the air- 

 chamber, but which was sot free as soon as tho 

 pressure was removed. Dr. Jaminet thought 

 the affections were due to physical exhaustion 



