MULLENIX: EIGHTH CRANIAL NERVE. 225 



part of a terminal organ at one view than is possible when the sections 

 are thinner. This renders unnecessary the mental reconstructions 

 from thin, serial sections, to which Kohner (:05) was driven in his 

 study of the conditions in the ear of the frog. It was on the basis of 

 such a combination of a great number of sections that he arrived at 

 his belief in the existence of an intracellular nervous network. 



A further advantage possessed by sections not less than 10 mikra 

 in thickness is that in such sections it is possible to trace axis cylinders 

 much farther toward the brain than with thinner sections. Sections 

 of a thickness much in excess of 10 mikra, on the other hand, present 

 conditions so complex as to render it difficult or impossible to interpret 

 them, owing to the great amount of nervous material which is brought 

 into view. 



By the application of a solution of the concentration already described 

 for the period stated it has been possible to eliminate, to a great degree, 

 the element of chance, which plays so large a part in older methods 

 of neurological technique, and to get fairly consistent and constant 

 results. The nervous elements are colored dark brown or black, 

 and the surrounding tissues are usually stained a light yellow, with the 

 exception of the nuclei and nucleoli, which, when preserved, are usually 

 darker in color. The sense hairs are commonly well preserved, as 

 shown in Figures 11, 12, 16 (Plate 3), 17, 22, 26, 27 (Plate 4), 31 (Plate 

 5). There is considerable variation in the effects upon the sense cells. 

 Like the basal cells and the basement membrane, they are usually 

 stained light yellow, in sharp contrast to the darker color given to the 

 nervous material. In some preparations, however, in which impregna- 

 tion is good, the epithelial cells show signs of having received harsh 

 treatment. I believe that this is due to the action of the ammonia 

 of the Bielschowsky's fluid. The structure of the sense cells may be 

 seriously altered, owing to the obliteration of cell boundaries, the 

 vacuolation of the cytoplasm, and the collapse of the nuclei. Such 

 material, while useful for tracing the courses of nerve fibres and making 

 out the forms of nerve terminals, is not to be relied upon to any great 

 extent in seeking to determine the relations between axis cylinder and 

 sense cell. Figure 16 (Plate 3) represents such a preparation. In 

 Figure 12 (Plate 3) a preparation is represented in which the nuclei 

 are not well preserved and there is considerable vacuolation, but the 

 cell boundaries are not obliterated. I have also obtained an abun- 

 dance of well impregnated material in which the cell boundaries are 

 clearly marked and the protoplasmic structures of the cell body are 

 not essentially unlike those shown in preparations made by methods 



