Literary Notices. cxxiii 



been carried to the surface. Thus we have the originally simple eye di- 

 vided into three portions : one central portion, in which the retinal cells 

 are superficial and two lateral portions in which the nerve-fibres are su- 

 perficial. The central mass is a simple eye and the two lateral masses 

 are inverted eyes. In some species of salpa these three parts are sepa- 

 ated, forming three eyes situated upon the anterior end of the brain. 



The author thinks these facts have a deep morphologico-phylogenetic 

 bearing. He thinks they make it less difficult to harmonize the simple 

 uninverted eyes with inverted ones. He proceeds as follows. To ho- 

 mologize the simple eye described above with the bladder-like eye of the 

 tunicates, he supposes that all observers (himself included) have over- 

 looked a flat layer of cells which cover the retina and which are continu- 

 ous with the pigment cells. If this hypothetical membrane exists, then 

 the lateral inverted eyes derived from .such an eye would also have an in- 

 vesting membrane. If this be true it is possible to give a morphological 

 explanation of the formation of the eye-ball. At the time of the forma- 

 tion of the lens let the retina and the pigment layer of the originally flat, 

 bladder-like, inverted eye grow upward and form a cup-shape body. Let 

 this cup be plugged by the crystalline lens and the major part of the 

 work is done. The author thinks that there is nothing improbable about 

 this supposition. 



The Composition of the Cerebro-spinal Fluid. i 



The author finds that the fluid is more strongly alkaline in the early 

 morning than at night and that the solid elements of the blood are in 

 greater amount in the morning. This fluid is more slowly affected by 

 substances introduced into the body than the general circulation, urine, 

 or humors of the eye. The results are thought to substantiate Ober- 

 steiner's theory of sleep. 



The Parietal Nerve. 2 



Abstracted for this journal by Mr. L. H. Cammack. 



In the October number of the " Anatomischer Anzeiger,'" Prof. Ber- 

 aneck has given a very complete and scholarly paper, containing his ar- 



1. Cavazzana, E. Ueber die Cerebro.spinalftuessigkeit. Centralblatt f. Physiol- 

 ogic, VI, 14. 



2. Sur le nerf parietal et la raorphologie du troisiememe (jeil des Vertebres, 

 Auat. Aijzeiger. VI, 21-22. 



