THEORIES OF SLEEP. 437 



life. A much more local disruption of connection, limited perhaps 

 to the cortex, might bo sufficient to explain the subjective condition 

 in sleep. At any rate, Duval's view is that the cortical cells are 

 capable of retracting or extending their processes so as to sever and 

 resume their relation with neighboring elements. Experimental evi- 

 dence in support of this theory is naturally slight. Wiedersheim has 

 described amceboid movements on the part of cells in the nervous sys- 

 tem of a small transparent crab. Of course it is only in such lower 

 forms that the living cells can readily be brought under the micro- 

 scope. Duval himself suddenly beheaded dogs that were awake and 

 others in anaesthesia and made histological preparations from the 

 brains. He believed he could distinguish the sleeping brain by the 

 more contracted and isolated appearance of its cells. 



The second histological theory of sleep, which has been said to be 

 quite opposed to the first, is that of the Italian neurologist, Lugaro. 

 Both demand the capability of amoeboid movement on the part of the 

 cells. But while Duval supposes that in sleep the cells have broken 

 their contacts, Lugaro supposes that they have made new contacts with 

 great freedom. At first thought this view seems unreasonable. A 

 multiplicity of contacts and added pathways in the brain might be 

 supposed to imply a richer and keener consciousness. But this would 

 be true only to a certain point. When the indiscriminate combination 

 had gone a step further mental confusion might be expected, then 

 fantastic associations and a meaningless mosaic of memories — prac- 

 tically a state of dreaming. Let the cells commingle their impulses 

 still more freely and consciousness will be lost, for the diffusion of 

 energy in the brain will result in a lessened intensity of flow in the 

 principal channels. If each cell scatters its communications in every 

 possible direction no definite effect in consciousness is to be looked for. 

 According to Duval, the cells which are affected in sleep can not dis- 

 charge; according to Lugaro, they may do so, but the resulting im- 

 pulses are utterly dissipated in a maze of by-ways. Waking, accord- 

 ing to Duval, is the resumption of intercourse among these cells; 

 according to Lugaro, it is the restriction of intercourse to habitual 

 and purposeful channels. 



There is no reason why we may not be eclectic in regard to these 

 two points of view. It may be that many paths are interrupted in 

 sleep, while others are opened. In the hypnotic state it is clear that 

 many paths are blocked, including those by which the will of the sub- 

 ject habitually asserts itself, while others, especially those making 

 connections between the auditory and motor areas, transmit impulses 

 with extraordinary efficiency. This condition is explicable if we sup- 

 pose that certain synapses are broken, as Duval imagines, and that 



