Literary Notices. lxxxix 



very large proportion of the cases of acute insanity we are forced to 

 fall back on the assumption of microscopic changes as yet beyond the 

 scope of our powers of observation, or to assume, as might perhaps 

 be done in accordance with the later pathologic theories, a toxic ac- 

 tion directly on the brain. To those who wish to hold to the theory 

 of microscopic changes in the brain, the comparatively recent re- 

 searches in the minute anatomy of the nervous system by Cajal, K61- 

 liker, Van Gehuchten and others may afford some suggestions. Gow- 

 ers, and more recently Ferrier, have emitted the supposition that de- 

 rangements of the terminal end-brushes of the spinal nerves may ac- 

 count for certain spinal diseases, Landry's paralysis, for example, 

 the pathology of which has thus far eluded our search ; and Tanzi in 

 a review of the recent progress of research in the anatomy of the ner- 

 vous system has suggested that the perfection or otherwise of contact, 

 or rather contiguity, of these processes to the nerve cells will account 

 for the facts of consciousness and mental capacity. According to his 

 theory he accounts for certain actions, once conscious and labored, 

 becoming unconscious and automatic by the supposition that the con- 

 tiguity of the nerve fibrils to the cells has reached its maximum and 

 thus affords the least possible interruption or hindrance to the nerve 

 wave, and by the same method of reasoning he explains the various 

 degrees of individual capacity for different kinds of work. It is not 

 difficult to see how this line of argument could be applied to psychic 

 derangements. It suggests an interesting, though rather difficult line 

 of microscopic research which may or may not be fruitful of results. 



The Evolution of the Preoral Lobe. 1 



The author, who has elsewhere attempted to show that the ascid- 

 ian larva is morphologically a preoral lobe homologous with the head 

 cavities and preoral coelom (+preoral pit) of Amphioxus and the pro- 

 boscis of Balanoglossus, considers that many indications point irre- 

 sistibly to the conclusion that the prime factor which must be recog- 

 nized in the evolution of the preoral lobe, from the relations which it 

 sustains in invertebrates to those which it holds in the Protochordata 

 and vertebrates is its complete emancipation from the central nervous 

 system. 



In annelids, molluscs and arthropods the preoral lobe is the seat 

 of the cerebral ganglion. This lobe (or apical plate) in the Trocho- 

 phore larvae of annelids and molluscs is the main if not the sole ele- 



'Willey, A. Anat. Anzeiger. IX, II. 



