90 MARIAN L. SHOREY 



Experiments with neuroblasts from Necturus were more satis- 

 factory, although I have failed to repeat successfully Professor 

 Harrison's experiment of developing nerve fibers in a drop of 

 lymph from the adult. 



The culture medium with which I obtained successful results 

 contained the following ingredients: 



4000 cc. tap water; 12 gm. beef extract; 



40 gm. peptone; 560 gm. gelatin. 



20 gm. NaCl; 



This was neutralized with NaOH, and, after cooking, 40 cc. of 

 1 per cent. HCl were added. Drop cultures were made by adding 

 either isolated cells or small portions of the medullary canal to 

 this. When placed in this medium the isolated cells were oval in 

 shape, with a perfectly even contour. Figs. 1 and 2 represent 

 two typical cells about forty-three hours later. These two cells 

 were examined at intervals for the next twenty-four hours, but 

 there was no appreciable change. From a small piece of the medul- 

 lary canal on the same slide, a mass of fibres were developing on 

 one side, and a scratch on the cover glass just beyond the end of 

 the longest fibre was noted, and used as a means of determining 

 the extent of growth. Twenty-four hours later this fibei had 

 crossed the scratch and grown for some distance beyond; the 

 other fibres had also increased in length. Fig. 3 represents the 

 mass of fibers at this time, the cells from which they arise not being 

 shown . 



To determine with certainty that these could not be lines of 

 coagulation or anj^ other similar phenomena, a dilute solution of 

 methylene blue was added and allowed to stand for a few moments. 

 On removing it the gelatin remained coloiless but the cells and 

 fibers were distinctly stained, and that the latter were outgrowths 

 of the former could not be doubted. 



The experiment was repeated, and although not always suc- 

 cessful, on two slides, I obtained many short fibres and a few 

 longer ones, with the characteristic change in the shape of the cells. 

 A few of these are represented in figs. 4 to 10. In all cases, after 

 a careful examination without staining, methylene blue was added 



