78 



Scientific Proceedings (64). 



there are frequently found instances of irregularity in nuclear 

 contour. These may amount at times to angular indentations. 



5. The nucleolus stains intensely basically but differs somewhat 

 in tint from the chromatin or tigroid substance in that with thionin 

 it appears distinctly a bluish dark blue while the chromatin and 

 tigroid substance with the same stain are of a purple tint. 



6. The staining of the primary dendritic trunk is variable in 

 all the types. At times the trunk may be followed easily to its 

 first or second divisions. But in other cells just as normal there 

 is only a very faint indication of the trunk. 



Types of the Purkinje Cell in the Dog. 1 



Type a. — The perikaryon is 25 y wide and 34 y long. The 

 nucleus has a mean diameter of 12 y. The nucleus shows a small 

 amount of chromatin irregularly distributed. The cytoplasm 

 shows a moderate amount of tigroid substance on a light back- 

 ground. This tigroid substance is not arranged as in the anterior 

 cornual cells. The masses are quite irregular in shape and in 

 distribution. Part of the cytoplasm may show little of this sub- 

 stance while in another locality it may be dense. 



Type (3. — The perikaryon is 22 y wide and 32 y long. The 

 nucleus has a mean diameter of 10 y. Both nucleus and cytoplasm 

 show a dark background. There is about as much chromatin in 

 the nucleus as there is tigroid substance in a field of equal area in 

 the cytoplasm. The arrangement of the tigroid substance is 

 more uniform than in type a. 



Type 7. — The perikaryon is 30 y wide and 35 y long. The 

 nucleus has a mean diameter of 12 y. The nucleus shows a small 

 amount of chromatin, irregularly distributed. The cytoplasm 

 has a light background. The tigroid substance is moderate in 

 amount and distributed in a fairly regular manner through the 

 cytoplasm. On account of the moderate amount of tigroid 

 substance the color tone of the cell is light and the nuclear cap 

 stands out in bold relief. 



Type b. — The perikaryon is 30 y wide and 35 y long. The 

 nucleus has a mean diameter of 12 y. The nucleus shows as 



1 The measurements are in all cases approximate only, and are given simply 

 as a guide to those not already familiar with the histology of the Purkinje cell. 



