No. 2.] CHAN-GES IN NERVE CELLS. 157 



except pigmentary degeneration ; and this may occur in almost 

 any specimen. No special amount of pigment was remarked 

 in the case in hand. Measuring a set (in this case 20) of 

 nuclei in a so-called normal cord for comparison gave the fol- 

 lowing result : — 



Nuclei of normal cord ; mean diameter . . 4-3o /^ 



Nuclei of hydrophobia cord ; mean diameter . . 3-i2 /x 



Volume per cent smaller 59 % 



I throw out the above merely as a straw which may serve to 

 show the direction of the current. We may have further use 

 for the material at some future time. 



I cannot close without mentioning by way of preliminary 

 communication the peculiar appearances found quite constantly 

 in osmic acid preparations of the ganglion cells of birds. They 

 are represented in Fig. 6, drawn throughout by the aid of a 

 camera lucida. A few are seen in Fig. 7 ; viz. the vacuoles with 

 sharp outlines and definite shape. The majority of the vacuoles 

 in Fig. 7 are easily seen to differ in these respects from those 

 in Fig. 6. In corrosive subUmate preparations they are seen 

 to be present, but are masked by granules. 



When first noticed, their definite form was thought to indi- 

 cate bodies of a crystalline nature in the protoplasm of the cells. 

 They were accordingly tested with polarized light, but were 

 found to be inert. 



Altmann (2) states that, whereas fats on treatment with 

 osmic acid become insoluble in alcohol, certain fatty acids 

 remain soluble. Therefore tissues hardened in osmic acid, if 

 they contain droplets or crystals of fatty acid after dehydration 

 in alcohol, present vacuoles holding the shape of the fatty acid 

 particles. It was thought that this might account for the lack 

 of any action upon polarized light. Accordingly a fresh morn- 

 ing sparrow was taken and the ganglion cells crushed out 

 quickly and examined under polarized light. The result was 

 doubtful. If any crystalline bodies were present, they vanished 

 almost instantaneously. In the liver, among fat droplets, which 

 shone brightly on the dark field, were a few shining particles 

 shaped like those in the ganglion cells, but these were quite 

 permanent. The same forms are found in the osmic acid liver. 

 In the oil gland, freshly crushed out, among sheaves of fatty 



