Literary Notices. xvH 



elements are round protoblasts in process of proliferation. The unipolar 

 stage is followed by a bipolar stage in which a process is formed that ex- 

 tends to a variable distance toward deeper parts of the retina. Cajal re- 

 gards the visual cells as different in kind from the neuroglia as well as the 

 true nerve cells for, as is claimed, in these cells the cellipetal and not 

 cellifugal process is first to develop. (A different intepretation than 

 this seems possible.) The so-called horizontal cells proved unamenable 

 to the silver method but two types were distinguished, one with fine 

 and the other with coarse axis cylinders. Two distinct sorts of bipolar 

 cells, one for the rods and the other for the cones are distinguished. 

 The second part of the paper is devoted to the structure of the retina 

 of birds. The so called association spongioblasts are supposed to be 

 connected with the centrifugal fibers whose existence is regarded as 

 proven. The principal type of ending, the pericellular nest, is very like 

 that of the so-called basket cell of the cerebellum. Cajal still maintains 

 as against Dogiel that anastomoses of nerve fibers do not occur in the 

 retina, and ascribes the evidence to the contrary to imperfect observa- 

 tion, c. L. H. 



PHYSIOLOGY. 

 The Function of the Protoplasmic Processes of Nerve Cells.* 



This article throws new light upon the function of the protoplasmic 

 processes of nerve-cells, a problem which neurologists have been inves- 

 tigating ever since Golgi announced that there was a structural differ- 

 ence between these processes and the axis- cylinder prolongation of a 

 nerve cell. 



The first part of the paper is a historical resume of the growth of 

 opinion on the subject. Among other things, the author makes the 

 following statements. Golgi still holds that the function of the den- 

 drites is purely nutritive. Although several early investigators thought 

 they had demonstrated the truth of his hypothesis, yet recent investiga- 

 tors do not hold this extreme view. Ramon y Cajal and Van Gehuch- 

 ten hold that both the ramifications and the distribution of the dendrites 

 fit them for the reception and communication of nervous impulses and 

 that that is undoubtedly their function. Lenhossek holds a similar but 

 not quite so exclusive view. K511iker holds that our present technique 

 does not yield an answer to the problem. 



^ Semi Meyer. Ueber die Function der Protoplasmafortsiitze der Nerven- 

 zellen. Berichte i'lbci' die Verhandlitngen der Koniglich Siichsischen Geselhchaft 

 der Wisscnschafteu zu Leipzig. 1897, V, VI, pp. 475-496, Taf. I, II. 



