ON THE STRUCTURE AND FUNCTION OF THE MAMMALIAN HEART. 465 



Experiments with Ancesthetics. — It will, perhaps, be best to take these two 

 sets of experiments together. Shortly summarised, they have been 

 made with the object of determining how the above-described points of 

 structure affect the working of the heart, and more especially what 

 practical use can be made of the knowledge gained in these observations. 



It is well known that in young animals it is exceedingly difficult to 

 produce any effect by means of chloroform — in fact, in my experiments I 

 have often found it almost impossible to an?esthetise animals only a few 

 days old. Gradually, as age increases, they become less refractory, and 

 at a few weeks old (in the case of kittens) chloroform produces the same 

 effects as in the adult. 



More than this, however, in the newly-born animal it is almost im- 

 possible, push the anaesthetic as you will, to produce stoppage of the heart, 

 though this is one of the accidents most to be feared in administering 

 chloroform to an adult animal. But even in the adult, if the thorax be 

 opened and the heart examined immediately after death by chloroform 

 poisoning, it will be found that, though the heart as a whole is quiescent, a 

 portion of it, the right auricle, is still beating. In other words, it is not 

 the initial stage of the beat which is absent ; the quiescence of the heart 

 is rather due to a failure in the transference of the beat already initiated 

 from auricle to ventricle. This failure occurs only in the adult or nearly 

 adult heart, and it has been shown that it is precisely in these adult or 

 nearly adult hearts in which the connecting link between auricle and 

 ventricle is reduced to a minimum. The failure of the heart's action, then, 

 may be supposed to be due to the failure of a strand muscle of compara- 

 tively small sectional area to convey to the ventricle a wave of contraction 

 started in the auricle. 



It occurred to me, then, that it might be possible in cases of chloroform 

 poisoning to so improve the conducting power of this strand of muscle as 

 to enable the waves of contraction to once again pass over the junction 

 and cause contractions of the ventricle. 



My experiments upon this point are at pi-esent incomplete, but I have 

 obtained results which lead me to hope that the research will not be 

 entirely without practical results. 



On recent Itesearches in the Infra-red Spectrum. 

 By S. P. Langley, B.G.L., LL.B. 



[PLATES II.-IV.] 

 [Ordered by the General Committee to be printed in exte7iso.'] 



I PRESENTED to the Association in 1882 at Southampton an account of 

 some researches made by means of the bolometer in the infra-red spectrum 

 formed by a glass prism ; but though these labours have continued with 

 occasional intermission during the past twelve years, it is, for reasons 

 which will be explained later, only within the past three years that any 

 notable advance has been made, and only within the past twelvemonth 

 that such a measure of success has been attained as justifies the present 

 communication. 



This is not the time to give any historical account of discovery in the 

 infra-red spectrum, but all those interested in the subject know that the 



1894. n H 



