FRANK MORRELL 387 



concentration oi the pyronin-positive material in a dense layer along the 

 inner surface of the cell membrane. Not infrequently the cytoplasmic 

 space between the membrane zone and the nucleus is considerably paler. 

 Such a concentration might be expected for an arrangement of protein 

 molecules capable of influencing the distribution of potential across the 

 membrane. It is not the concentration pattern to be expected as a result of 

 simple tiecrease in cell volume. Note also the suggestion of a bilobed 

 nucleus. Andrew (1955) has considered the occurrence of bilobed nuclei in 

 mouse Purkinje cells to indicate an abortive attempt at amitotic division in 

 nerve cells subjected to certain forms of stress. The primary lesion (Fig. 

 1 2 A) is surrounded by cells of a similar appearance. The contralateral 

 homologous region of the same section (Fig. 12B) is less deeply stained 

 than in sections slightly further away from the primary histological lesion, 

 (compare Fig. 9). Similarly, the electrical records indicated that the most 

 active discharge in the mirror region was not homotopic with the centre 

 of the ethyl chloride lesion but rather with its periphery just as the 

 primary electrical discharge is at the periphery rather than the centre o^ 

 the primary lesion. Adjacent sections treated with ribonuclease show loss 

 of almost all the tinctorial properties of these cells. 



Although these are still preliminary observations, some controls have 

 been introduced to insure that the histological changes are not artifactual. 

 One might argue, for example, that such nests of deeply stained cells are 

 occasionally (although rarely, in our experience, if the brain is properly 

 fixed) found in normal brain. These may be due to random variations in 

 penetration of dye, fixation of material, or even in the capacity of the cell 

 to take the stain for reasons other than those suggested in our experi- 

 mental procedure. One might also consider that such cells were damaged 

 in the course of removal of the brain or in the fixation procedure and that 

 the deep stain indicates nothing more than pyknosis. Most of these 

 objections may be countered by the following evidence: (i) The densely 

 staining cell aggregates were seen in different cortical zones in each of the 

 experimental animals and consistently were related to the electrical focus 

 rather than to any particular cortical zone. (2) Adjacent sections from the 

 same animal indicated that stained areas could be superimposed, thus 

 excluding random staining of the slide. (3) The brains were perfused with 

 fixatives while the animals were under deep anaesthesia but still alive. This 

 procedure minimized cell changes due to poor fixation. Moreover, it 

 would seem unusual that fixation artifact would vary in location from 

 animal to animal in a manner precisely concordant with variations in the 

 site of electrical discharge. There remains the argument, which may be 



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