254 E. VICTOR SMITH 



ganglia of seven kinds of birds. In the raven, goldfinch, and 

 cardinal bird he describes finely granular unipolar cells of variable 

 shape and two varieties of nerve fibers, large and small, the coarse 

 fibers running through the ganglion without being connected 

 with the ganglion cells. In the sensory ganglia of the chick only 

 coarsely granular unipolar cells were observed surrounded by 

 tough pericellular tissue. In swimming birds (duck and goose) 

 the cells were bullet-shaped, unipolar, and very finely granular. 



van Gehuchten ('92 a and '92 b) investigated conditions in 

 embryos of the duck and the chick. The cells were oppositi- 

 polar up to the twelfth day of incubation. In twenty-day em- 

 bryos he found oppositi-polar, unipolar, and transitional stages. 

 In the adults he declares all cells to be unipolar. He found similar 

 conditions in ganglia of the fifth, the ninth, and the tenth. 



The observations of von Lenhossek ('92) indicate that the 

 cells of the sensory ganglia of the seven-day chick are all bipolar, 

 and ('94) that the first tendency toward unipolarization is seen 

 on the ninth day ; by the fourteenth to fifteenth days of incuba- 

 tion unipolar cells are numerous. Cajal ('93) found multipolar 

 cells in the spinal ganglia of the embryo chick and concluded that 

 they later develop into those of the ordinary type. 



Huber ('96) observed cells with accessory processes in the dorsal 

 spinal ganglia of the chick. These are not of frequent 

 occurrence. 



Timofeew ('98) describes chiefly the internal structure of sen- 

 sory ganglia showing a fibrillar reticulum of the cell body. He 

 found small tigroid bodies, with fibers that form networks, to 

 be characteristic of spinal and sympathetic ganglia of birds. 

 The cells range from 8 to .40/x in diameter. Two nucleoli were 

 regularly seen in each nucleus, one of which took an acid and the 

 other a basic stain. 



Levi ('05, '06 and '08) made observations on the spinal ganglia 

 of pigeon embryos and found bipolar spindle shaped cells with 

 three processes. In the later stages, when the cells become uni- 

 polar, the third process appears to unite with the axis cylinder and 

 become a part of it. In other bipolar cells there issued fine col- 

 laterals from the two processes. He could not confirm their 



