The common reading ἵνα μὴ τοῦ ψύχους πλείων γένηται ὁ χρόνος, ἀλλ᾽ ἵνα αἱ νύκτες, κ.τ.λ. gives a meaning contrary to the facts.  The translation follows the mss. Roe, Casaubon, which omit μή and for ἀλλά read καί.  Compare Whewell’s Astromony, p. 22:  “The length of the year is so determined as to be adapted to the constitution of most vegetables:  or the construction of vegetables is so adjusted as to be suited to the length which the year really has, and unsuited to a duration longer or shorter by any considerable portion.  The vegetable clock-work is so set as to go for a year.”  Ibid. p. 34:  “The terrestrial day, and consequently the length of the cycle of light and darkness, being what it is, we find various parts of the constitution both of animals and vegetables, which have a periodical character in their functions, corresponding to the diurnal succession of external conditions, and we find that the length of the period, as it exists in their constitution, coincides with the length of the natural day.”