498 PHYSIOLOGY CHAP. 



XVI. Periodic respiration is a physio-pathological phenomenon 

 intimately connected with the difficult problem of the nature of 

 the normal rhythmical functions of the respiratory centres. The 

 first to perceive the importance of this point was Traube, to whose 

 initiative is due the harvest of literature on this interesting 

 subject, which we have briefly summarised. 



In 1879 we drew up an exhaustive refutation of Traube's 

 doctrine, and of the more complicated theory opposed to it by Filehne 

 in 1874, showing the absolute inadequacy of these hypotheses to 

 account for the whole of the experimental data, and the great 

 variety of clinical forms, which the respiratory phenomenon may 

 assume. We showed that it was impossible, in face of the proved 

 facts, to solve the problem by the postulate usually admitted and 

 defended, to the effect that the capacity and functional activity of 

 the central mechanisms of respiratory rhythm are always in 

 direct and immediate dependence upon extrinsic conditions of 

 stimulation and nutrition ; i.e. in other words, that the said 

 centres merely transform what at any given moment they receive, 

 in the same degree and with the same rhythm at which they 

 receive it. The experimental evidence shows that there is, 

 between the external action and the reaction, a whole, complex, 

 cheniico- molecular, internal process, of which we are aware in 

 virtue of its results, but as to the laws of which we are entirely 

 ignorant. 



The obvious facts on which we have insisted amply suffice to 

 prove that there is no ratio between the duration and the degree 

 of pulmonary ventilation represented by the groups and the 

 duration of the pauses ; that the form of the groups may vary 

 greatly and in opposite ways that are not comparable inter se ; 

 that periodic respiration may be observed even where no gas 

 exchanges between the atmosphere and the blood are possible 

 all these clearly demonstrate the fundamentally automatic 

 character of the function of the bulbar respiratory centres. " The 

 different forms that may be assumed by the respiratory rhythm, 

 including those of periodic grouping, are merely the external 

 expression of corresponding modes of oscillation in the nutritional 

 processes, which are carried on within the depths of the respiratory 

 centres " (Luciani, 1879). 



Normally, however, these centres, in addition to an automatic 

 excitability, are provided with a most delicate reflex excitability, 

 which enables them immediately to react even to the slightest 

 external stimulus, thus giving rise to profound modifications in 

 the form and rhythm of the automatic excitability as dependent 

 upon the internal impulses. Our task is now to determine (as 

 precisely as possible) what are the relations of co-existence 

 of these two forms of excitability, both in normal conditions, and 

 under exceptional or abnormal conditions, of the respiratory centres. 



