82 NATURAL SCIENCE. February, 



On isolating, after Rosenthal's method, a section of the chest-wall, 

 including the second to the fifth ribs, on one side, so that it was 

 completely separated from the ribs above and below and from the 

 sternum in front, and on dividing all the muscles connecting this section 

 with the vertebral column, so that the only muscles which could act 

 on it were the intercostals, it could be seen that the ribs in the isolated 

 section were strongly raised at each inspiration, the movement ceasing 

 when the intercostal nerves were divided. Further, when the external 

 intercostals were divided in this section, leaving the internal intercostals 

 intact, the ribs were passive in inspiration, but were drawn down in 

 expiration ; this movement ceased when the internal intercostals were 

 also divided. In a still more elaborate series of experiments the 

 authors succeeded, in cats, in extirpating the entire musculature of 

 the chest-wall with the exception of the intercostals and the 

 triangularis sterni ; even the intercartilaginei were severed. The 

 phrenic nerves were divided. Pneumothorax occurred in two of the 

 experiments ; in two it was successfully avoided. In all cases active 

 respiratory movements occurred, brought about solely by the action 

 of the intercostal muscles, and it was clearly manifest that the 

 external intercostals raised the ribs, while expiration was not merely 

 a passive recoil, but was produced by an active contraction of the 

 internal intercostals. In one case the animal breathed quietly and 

 peacefully for ten minutes after section of the phrenic nerves. 



These very interesting and complete experiments should set at 

 rest the question of the action of the intercostal muscles during forced 

 inspiration and dyspnoea. It is perhaps not absolutely safe to argue 

 from cats and rabbits to man, but the disposition of the muscles is 

 substantially similar in man, and no good reason can be shown in this 

 case for not so arguing. It ma}' not be quite safe to interpret the 

 phenomena of quiet respiration under normal conditions by the light 

 of the facts observed during the dyspnoea of such severe and abnormal 

 conditions as have been above described. But it is incredible that 

 muscles which have one definite action in dyspnoea should have a 

 different action in calm breathing, and there is at least a strong 

 presumption that their action is similar in character, though less in 

 degree. And so, after years of wandering, we come back to the old 

 familiar hinged rods and rubber bands, glad to find that, after all, 

 they were very near the truth. 



A New Giant-Bird. 



Some years ago it was announced by Professor Stirling that a 

 number of skeletons of Diprotodon and other extinct marsupials had 

 been discovered exposed on the surface of the ground at Lake 

 Callabonna in South Australia, and that the remains of a large extinct 

 struthious bird occurred associated with these mammals. Further 

 details of this remarkable find have been awaited with some im- 



