No. 2.] CHANGES IN NERVE CELLS. 145 



general appearance." Probably the same statement holds good 

 for individual birds and bees. Nevertheless, we are compelled 

 to abandon this safe precaution of using only cells from differ- 

 ent sides of the same animal. It would be clearly impossible 

 to remove a spinal ganglion from one side of a bird or one half 

 of a bee's brain in the morning and the corresponding parts at 

 night, without seriously interfering with the animal's normal ac- 

 tivity. Nothing of the sort was attempted. However, wherein 

 the rigidity of the method is weakened by comparison of the 

 cells of different animals, it is possible to strengthen it by mak- 

 ing observations more numerous. 



Aside from this the method of operation is essentially the 

 same as that already described. ^ The birds, sparrows and swal- 

 lows, were shot morning and evening at as nearly the desired 

 time as possible, and the parts to be studied were excised on 

 the spot. The pigeons were decapitated, no anaesthetic being 

 used. A pair of spinal ganglia in each case were preserved in 

 osmic acid, one per cent solution being used as formerly. The 

 time was shortened to two hours' immersion on account of the 

 small size of the ganglia. The other parts were preserved in 

 saturated corrosive sublimate solution at 40° C. for four hours. 



Both male and female birds were employed, but, with one 

 exception, males were compared with males and females with 

 females. 



Res2ilts. 



The following table gives the results of six experiments for 

 the parts studied. Sections were taken perpendicular to the 

 surface of the cerebellar and occipital cortex, longitudinal sec- 

 tions being made of the spinal ganglia. 



The fact to strike one first upon examination of the speci- 

 mens or the table is the great amount of change due to 

 a day's fatigue. This is seen to exceed anything obtained by 

 artificial stimulation in almost all cases. The highest per cent 

 shrinkage of nuclei, 69.7 per cent, is found, strangely enough, in 

 the occipital cortex of a female sparrow April 22, after a long 



^ One thing, however, has escaped my attention, viz. the hardening, in osmic acid, 

 of the specimens to be compared was not done at constant temperature. A slight 

 difference, hence, between morning and night temperatures may have had some influ- 

 ence upon the results. That this difference has not complicated matters seriously is 

 shown from the fact that other portions of the same animal hardened in corrosive 

 sublimate at 40° C, and hence, not amenable to temperature variations, give results 

 equally good. 



