222 



Mary Isabelle Steele 



most instances, however, a longer or a shorter stump remained. 

 It is impossible to determine by surface examinations how large 

 the stump was originally for it decreases in size after the operation. 

 Sometimes the stump of the optic nerve and ganglion shrinks to 

 two-thirds of its original volume. Fig. 31 shows a short rounded 

 stump which evidently contains a part of the proximal segment of 

 the optic ganglion. The stump, originally as broad as the base of 

 the opposite eye, has, after one moult twenty-three days after the 

 removal of the eye, shrunk to one-half of the original mass. The 

 remains of the optic nerve seem to come flush against the end of 

 the stump, showing that no new tissue has been developed distal 

 to it. Fig. 39, thirty-two days after the injury, shows a stump 

 more than one-third the length of the normal eye. Yet sections 

 show no indication that any definite structure is being regenerated. 

 It is useless to multiply figures on this phase of the question. They 

 only serve to show how completely is lacking any indication of 



regeneration. 



The following table will serve to show that time cannot be 

 considered the chief factor in regeneration. 



The last five examples given in the preceding table are taken 

 from the same series. Evidently the conditions here were more 

 favorable than usual. The original number of the series was 

 twenty-five. Six of these died either from the efi^ects of the oper- 

 ation or soon afterwards. Of those remaining five others were 

 lost through an accident. Out of the fourteen for which there is a 



