When the subjects are placed in the order that I have suggested, there is an end of that promiscuous and random choosing that the arrangement of the Commissioners suggests and encourages.  To the specification of the five heads of natural science, it is added, that the whole of the 1,000 marks may be gained by high eminence in any two; as if the choice were a matter of indifference.  Now, I cannot think that this suggestion is in conformity with a just view of the continuity of science.  When the sciences are rightly arranged, there is but one order in the mother sciences; if we are to choose a single science, it must be (with some qualifications) the first; if two, the first and second, and so on.  To choose one of the higher sciences, Chemistry or Physiology, without the others that precede, is irrational.  Indeed, it would scarcely ever be done, and for this reason.  A man cannot have mastered Physiology without having gone through Physics and Chemistry; and, although it is not necessary that he should retain a hold of everything in these previous sciences, yet he is sure to have done enough in both one and the other to make it worth his while to take these up in the examination.  So a good chemist must have so much familiarity with Physics, as to make it bad economy on his part not to give in Physics as well.  The only case where an earlier science might be dropped is Mathematics; for although that finds its application extensively in Physics and indirectly in Chemistry, yet there is a very large body of physical and chemical doctrine that is not dependent upon any of the more difficult branches, so that these may admit of being partially neglected.  But, as an examination in Physics ought to include (as in the London University) all the mathematical applications, short of the higher calculus, it is not likely that Mathematics would be often dropped.  So that, as regards the mother sciences, the variation of choice would be reduced to the different lengths that the candidate would go in the order as laid down.  As regards the other sciences—­those of classification and description—­the selection might certainly be arbitrary to this extent, that Mineralogy, Botany, and Zoology might each be prescribed alone.  But then, whoever presented one of these would also present the related mother science.  He that took up Mineralogy, would infallibly also take up the three first as far as Chemistry.  He that gave in Botany would probably take up Physiology, although not so necessarily, because the area of plant Physiology is very limited, and has little bearing on descriptive Botany, so that anything like a familiarity with Physiology might be evaded.  But he that took up Zoology, would to a certainty take up Physiology; and very probably also the antecedent members of the fundamental group.  As to Geology, it is usually coupled with Mineralogy, although involving also a slight knowledge of Botany and Zoology.  A competent mineralogist would be pretty sure to add Geology to his professional subjects.