HISTOLOGY OF SENSORY GANGLIA OF BIRDS 255 



presence in the adult. In 1906, he described lobed cells in cere- 

 bro-spinal ganglia of the tenth (see my observations on the owl). 

 In the same ganglia he found a few fenestration cells, also a small 

 number with accessory processes and delicate collaterals on both 

 processes. In his extensive paper of 1908 he deals with the his- 

 tology and histogenesis of cerebro-spinal ganglia in all classes of 

 vertebrates. That part devoted to the ganglia of birds is rela- 

 tively brief. It includes observations on the Gasserian (semi- 

 lunare) and vagus (plessiforme) ganglia of the adult hen, and the 

 adult domestic duck, also the spinal gangha of the duck, and 

 sensory ganglia of the six-day chick and of the six-day duck 

 embryos. In the Gasserian of the hen he finds the cells of the 

 usual type, but, in the vagus of the same bird he found oppositi- 

 polar cells predominating and only a few transition stages between 

 that condition and unipolar. In the vagus of the duck, condi- 

 tions were reversed, most of the cells were unipolar with T and 

 Y branching processes, and bipolars were infrequent. In duck and 

 chick embryos he noted some details as to variation in the cells, 

 but found in the younger stages oppositi-polar cells, and in older 

 individuals transitional stages and a few unipolars. 



\ 



III. OBSERVATIONS 



The material used in my observations consisted of the spinal, 

 ninth, tenth and Gasserian ganglia of the chick; the spinal, eighth, 

 tenth and Gasserian of the screech owl; the spinal, ninth, tenth 

 and Gasserian of the goose, of the duck and of the pigeon respec- 

 tively; the spinal and Gasserian of the turkey; and the spinal of 

 the sparrow. 



In addition to my own preparations I had the use of serial 

 sections of the chick and duck prepared by the Cajal method by 

 Miss Enid Hennessey. 



Of the fixitives employed two were used extensively, ammonia- 

 cal alcohol and 5 per cent formalin. In the alcoholic fixitive the 

 amount of ammonium hydroxide was varied, from a few drops in 

 50 cc. of absolute alcohol, to 5 cc. of the ammonium hydroxide 

 in 100 cc. of 95 per cent alcohol. The best results were obtained 

 from material fixed in the 95 per cent alcohol with 5 per cent 



