No. 2.] CHANGES IN NERVE CELLS. 147 



hard day of nest-building. An egg was found in the lower por- 

 tion of the oviduct. The next highest percentage, 64 per cent 

 and 64.5 per cent, expresses the amount of fatigue in the spinal 

 ganglion cells of the same bird and in the cells of Purkinje, a 

 male swallow, June 10. Barnyard pigeons, fed a little grain twice 

 a day, show considerably less fatigue than the wild birds. 



As far as my work would permit, some account of the activity 

 of the birds was kept during the day of an experiment ; and a 

 day suited to the purpose of the experiment was chosen. 



Experiment I was made early in December, toward the end 

 of a cold blustering snowstorm. Sparrows keep under pretty 

 close cover while such a storm continues, and at its close may 

 be seen out in force and actively in search of food. Advantage 

 was taken of a case of this kind ; and the difference between 

 the cells of the spinal ganglia, the only part taken, morning 

 (Fig. 6) and evening (Fig. 7), is readily seen by comparison. 

 Although not showing the highest shrinkage per cent, the cells 

 of sparrow 2 (Fig. 7) do present a somewhat more striking state 

 of dilapidation than those of sparrow 6, and hence were chosen 

 for the plate. I suspect also that an individual complication is 

 present here, in the way of incipient starvation, as the crop of 

 this sparrow was empty, and there was little food in the gizzard, 

 and this at night when both are usually well filled. The proto- 

 plasm is seen to be extremely vacuolated and the nuclei much 

 shrunken. The peculiar clear spaces which form such a marked 

 feature in the cells of sparrow i (Fig. 6) are somewhat aside 

 from the line of our thought at present, and will be discussed 

 on a later page. 



Experiment II was made about the same time, and is simply 

 confirmatory of Experiment I. Shrinkage of the nuclei in the 

 pigeon is nearly as marked as in the sparrow. Vacuolation of 

 protoplasm is not so striking, although present. 



Experiment III deserves special remark. It was made with 

 the single purpose of confirming Experiments I and II. But 

 on the morning of February 17, shortly after sparrow 3 had 

 been shot, it began to rain, and continued nearly the whole day, 

 a steady, warm, foggy spring rain. In the dense cover of the 

 pine trees over my window the sparrows spent the day scolding 

 and chattering at a great rate. None were observed flying 

 about. At first I decided to abandon the experiment, thinking 



