NEUROTOXINS OF SNAKE VENOM 155 



diffuse staining begin to disappear and leave a skeleton cell, with its margin, 

 the reticulum, and nucleus being somewhat deeply stained but very well 

 differentiated. The staining later becomes gradually less intense until we 

 reach the stage in whicli the cell is little more then a shadow of its former 

 self — the typical "ghost" cell. Vacuoles next appear in the body of the 

 cell and its margin becomes indented as if httle pieces had been snipped out. 

 Then portions of the cell disappear altogether and leave little more than a 

 nucleus with the remains of the cell reticidum attached to it. All this time 

 the nucleus, at least in a large proportion of the cells, seems to be little affected 

 otherwise than is shown by a varying intensity of its staining. It remains 

 central, is only exceptionally found at the periphery of the cell, and though 

 it is sometimes lost to view in the diffuse staining of the earlier stages it is 

 almost always to be seen in the later stages of degeneration. Vacuolation is 

 most seen in the pale (ghost-cell) stage, but it is also to be met with in the more 

 deeply stained cells. The connective tissue elements of the gray matter 

 seem to play a somewhat secondary part in this degenerative process. They 

 may be slightly increased in number around the ganglion cell in its earlier 

 stages of chromatolysis, but this increase is not considerable and it is not till 

 vacuolation comes on and the cell begins to break up that they are seen to 

 cluster definitely around the disappearing cell. During this later stage, and 

 sometimes at an earlier stage, they are found indenting the margins and are 

 sometimes inside the body of the cell. 



The chromatolytic changes just described appear to be imiformly most 

 advanced in the smaller cortical cells and in the cells of the more central 

 group in the anterior horns of the cord. The larger cortical cells and certain 

 of the cells in the lateral groups of the anterior horns seem to be considerably 

 more resistant to the toxin, for they are slower in showing degeneration, and 

 when it does appear it is hardly ever so extreme as in those other cells. Of 

 the motor nuclei in the pons and medulla the ganglion cells of the third and 

 fifth nuclei were usually affected about equally with those of the cortex and 

 cord. But the seventh, tenth, and twelfth nuclei showed changes less often 

 at a later period, and of a less intensity, than any of the other motor cells in 

 any part of the central nervous system. 



In addition to the above description they found that the venom of Enhy- 

 drina valakadien, when allowed to act for several hours, produces granular 

 disintegration of myelin and fragmentation of axis-cylinder, thus showing its 

 widespread action on the whole nervous system, not only on ganglion cells, 

 but also on nerve fibers. 



