He explains his choice in lines 8-9 on p. 364 of the paper:

"This metric has the curvature $-4$ for it is obtained from the hyperbolic metric by the transformation $w'=w^{1/2}$ ."

Remarks. By more sophisticated choices of metrics later authors, M. Bonk (MR0979048) and Chen and Gautheier (MR1428103) were able to improve Ahlfors's estimate of the Bloch constant.

He explains his choice in lines 8-9 on p. 364 of the paper:

"This metric has the curvature $-4$ for it is obtained from the hyperbolic metric by the transformation $w'=w^{1/2}$ ."

Remarks. By more sophisticated choices of metrics later authors, M. Bonk (MR0979048) and Chen and Gauthier (MR1428103) were able to improve Ahlfors's estimate of the Bloch constant.

He explains his choice in lines 8-9 on p. 364 of the paper:

"This metric has the curvature $-4$ for it is obtained from the hyperbolic metric by the transformation $w'=w^{1/2}$"

Remarks. By more sophisticated choices of metrics later authors, M. Bonk (MR0979048) and Chen and Gautheier (MR1428103) were able to improve Ahlfors's estimate of the Bloch constant.

He explains his choice in lines 8-9 on p. 364 of the paper:

"This metric has the curvature $-4$ for it is obtained from the hyperbolic metric by the transformation $w'=w^{1/2}$ ."

Remarks. By more sophisticated choices of metrics later authors, M. Bonk (MR0979048) and Chen and Gautheier (MR1428103) were able to improve Ahlfors's estimate of the Bloch constant.