CH. L.] SLEEP AND NARCOSIS 745 



all rest upon the flimsiest foundations, and none has yet been found 

 to stand experimental tests. 



Then there are what we may term histological theories of sleep, 

 and these are equally unsatisfactory. The introduction of the Golgi 

 method opened a fresh field for investigators, and several have 

 sought to find by this method a condition of the neurons produced 

 by narcotics such as opium and chloroform, which is different from 

 that which obtains in the waking state. 



Demoor and others found in animals in which deep anaesthesia 

 has occurred, that the dendrites exhibit moniliform swellings, that 

 is, a series of minute thickenings or varicosities. On the strength 

 of this observation, what we may call a biophysical theory of 

 sleep has been formulated ; in the waking state, the neighbouring 

 nerve units are in contact with each other ; transmission of nerve 

 impulses from neuron to neuron is then possible, and the result is 

 consciousness ; during sleep the dendrites are retracted in an 

 amoeboid manner ; the neurons are therefore separated, and the result 

 is unconsciousness. 



Lugaro, on the other hand, takes the precisely contrary view. 

 He was not able to discover moniliform enlargements, and his bio- 

 physical hypothesis is that the interlacing of dendrites is much more 

 intimate during sleep than during consciousness. He therefore 

 explains sleep by supposing that the definite and limited relation- 

 ships between neurons no longer exists, but are lost and rendered 

 ineffective by the universality of the connecting paths. It is not 

 very difficult to explain such divergence of views, for they both 

 depend mainly on observations made by a single method ; and the 

 method itself is open to objection. It is one which gives even in the 

 same brain most inconstant results, and is not calculated to show 

 much more than an outline of a few of the cells and their branches. 



A more satisfactory histological investigation of the effect of 

 anaesthetics on nerve-cells was carried out by Hamilton Wright. 



He used rabbits and dogs, and subjected them to ether and 

 chloroform narcosis for periods varying from half an hour to nine 

 hours. In both animals he found that the nerve-cells are affected, 

 but in rabbits much more readily. This accords quite well with 

 what is known regarding the susceptibility of rabbits as compared to 

 dogs towards the influence of these narcotising agents. In a rabbit, 

 the nerve-cells, especially of the cerebrum, show changes even after 

 only half an hour's anaesthesia, but in dogs at least four hours' anaes- 

 thesia must be employed. By the Golgi method the moniliform 

 enlargements can be seen. These become more numerous, larger, 

 and encroach more and more on the dendritic stems, the longer the 

 anaesthesia is kept up. The accompanying illustrations show the 

 appearances seen (fig. 457). 



