STUDIES IN THE RETINA. 309 



typical multipolar ganglion ic cells^ occur here and there in 

 the higher Mammalia as if abnormally (see, e.g., the figures 

 Nos. 22 and 23 in Borysiekiewitz's ' Untersuchungen/ 1887).^ 

 Again, the nuclei forming the innermost row of the middle 

 nuclear layer along the outer edge of the inner reticular 

 layer, frequently have a slight trace of associated cytoplasm, 

 usually only on their proximal sides, and looking as if it had 

 come through the inner reticular layer and had left a trail 

 running radially into that layer. 



Nuclei with such trails of granular cytoplasm, and, perhaps, 

 a few here and there entangled in the Midler's fibres, as 

 explained in Part V, p. 59, are, so far as I can see, the only 

 foundation for the so-called " bipolar ganglion cells " of the 

 middle layer shown in all the diagrams as radially arranged, 

 spindle-shaped cells. So far as my experience goes, these 

 diagrammatic bipolar cells of the middle layer have no more 

 real existence as fixed morphological elements than have the 

 multipolar ganglionic cells described above. The only nuclei 

 of the retina that are suspended in the way shown in the 

 diagram — viz. within a spindle-shaped mass of cytoplasm, 

 which in no case could be the granular cytoplasm we have 

 been referring to, but rather a strand of the syncytial frame- 

 work — are : (1) those forming the still undifferentiated rim 

 in young eyes (cf. Part III, p. 33, and fig. 24, illustrating 

 this paper) ; and (2) those forming' the outer nuclear layer, or 

 layer of rod-nuclei, when it is several rows thick. With the 

 former of these exceptions, the nuclei of the middle layer 

 of the retina are not only not surrounded by granular cyto- 

 plasm, they are not even wrapped closely round by any portion 

 of the syncytial framework nor suspended on strands of the 

 same; but they are somehow supported within the meshes 

 of the retinal syncytium as in so many perinuclear spaces, 

 large or small, according to the age and condition of the 

 eye. How these apparently free nuclei were suspended and 



1 In retroniYzon, tlie outermost row of nuclei of tlic middle layer always 

 have a quantity of granular niat,ler associated with them, but these "cells" 

 have no ramifications. 



