On Growth and Form

by D'Arcy Wentworth Thompson

That is to say, the time taken to produce a given result at {115} 10° was (on the average) somewhere about 55·6 ⁄ 16·7, or 3·33, times as long as was required at 20°.

Fig. 28. Diagram shewing time taken (in days), at various temperatures (°C.), to reach certain stages of development in the Frog: viz. I, gastrula; II, medullary plate; III, closure of medullary folds; IV, tail-bud; V, tail and gills; VI, tail-fin; VII, operculum beginning; VIII, do. closing; IX, first appearance of hind-legs. (From Jenkinson, after O. Hertwig, 1898.)

We may then put our equation again in the simple form, {116}

x¹⁰ = 3·33.

Or,

10 log x = log 3·33 = ·52244.

Therefore

log x = ·05224,

and