32 Journal of Comparative Neurology. 



known, symbolizes the nerve ganglia as so many colonies of inde- 

 pendent vital beings like protozoans with common stalks. 



The most recent theory concerning the physiological cause 

 of sleep is that of Meynert, which is repeated in his latest lec- 

 ture. He says : " As we discover that the cell colonies of the 

 axial portion of the brain at one movement put forth feeble ac- 

 tivities compared to those of the cortex and again the situation 

 is reversed, we must recollect that of the myriads of cortex 

 cells capable of consciousness all are never simultaneously 

 awake but the greater number are aKvays, in the language of 

 Fechner, immersed in partial sleep. Consciousness is never an- 

 imated by all its images and impulses at once, but rather only 

 those elements which are wide awake, i. e., according to Fech- 

 ner, are attentive, are the sustainers of the momentary conscious- 

 ness. As the animal in its hibernation sleep is in a condition 

 of depressed nutrition and respiration, so the nutritive condition 

 of the waking cortical cells is different from that of the sleeping. 

 The work produced by a cerebral cell we call its state of irrita- 

 tion. Virchow has shown that, in the case of the epithelium of 

 the kidney, the cells expand when irritated, the muscle ex- 

 pands when excited, and the nerve cell must, in like man- 

 ner, through its molecular activity, exert a nutritive attraction 

 on the protoplasmic tissues when excited and in greater 

 activity, as an accompaniment of which its excitement rises, 

 according to Fechner, above the threshold of consciousness. 

 In the most characteristic activity of the brain, such as the 

 delicate play of association, in which state only a few out of 

 vast numbers of cells are active and these, through the excita- 

 tion of associational fibres, call into activity cells in a widely 

 separate area either simultaneously or in a definite serial con- 

 nex, this selective nutrition can only be produced by an indi- 

 vidualized suction of the elements." 



This idea of a vital-endosmotic nutritive activity or "cell- 

 suction" receives an anatomical support from the recent discov- 

 eries by means of Golgi's method which demonstrate that the 

 nerve cell is always provided with a vast number of fine tubular 

 fibrils which tend to collect about blood-vessels and lymph 



