450 



Messrs. L. Hill and M. Greenwood, Jun. [Jan. 16, 



the joints and muscle of the limbs and back were carried out regularly. On 

 emerging from the cylinder, beyond a few " picotements," no unpleasant 

 symptoms were noticed. 



On the next day the subject wrote as follows : " The only place I did not 

 move and massage was the front of the chest, where I have plenty of 

 subcutaneous fat. In the evening painful places were felt in the sub- 

 cutaneous tissues of the anterior thoracic region ; one spot under each 

 nipple, one across the right side of the chest about the level of the ensiform 

 cartilage, another above the left axilla in front, and one over the right upper 

 arm in front. A red or purplish rash appeared over these tender places. 

 They felt like a spot in which a subcutaneous injection of water has been 

 made. Next morning the tenderness was better but still evident, and the 

 rash was subsiding." 



Forty-eight hours after the experiment this purpuric rash was still 

 discernible, and was shown to Dr. W. Bulloch and other pathologists. An 

 eruption occurred in a very severe case of caisson illness seen by Heller 

 Mager and v. Schrotter (13). They give a plate of the eruption, which is 

 described in these terms : " Haut der linken Schulter und des linken Armes 

 an der Ausseuseite, besonders in der Gegend des Olekranon und des 

 iiusseren Condylus sowie in der Gegend des Biceps mit lividen, blaulich- 

 rothen netzformig verzweigten, inselformigen Flecken bedeckt, ebensolche 

 auch am Handrucken." The arm of this sufferer was much swollen and 

 intensely painful. These observations then show the extreme importance 

 of active movement and massage during decompression ; instructions should 

 be given to all caisson workers to perform such movements while in the 

 air lock. 



We believe the tenderness and the rash were caused by small bubbles 

 embolising the vessels of the subcutaneous fat in the case of L. H. The pair 

 felt by M. G. was probably due to small bubbles in the nerve sheaths in the 

 first case, in the knee joint in the second. 



Part II. 



The next stage of our investigation was devoted to an inquiry as to the 

 changes in the percentage of alveolar C0 2 under the altered conditions. 



We have employed the method described by Haldane and Priestley (14) 

 The subject breathes through a wide-bored rubber tube ; after a normal 

 expiration he expires deeply and then closes the end of the tube with his 

 tongue. A sample was taken from the wide tube into Haldane's portable 

 C0 2 analyser, and examined. A bench fitted up in our cylinder enabled the 

 subject to collect and examine samples with ease. It may be remarked that 



