11.  Having got thus much of (partly conjectural) idea of the mechanical structure of marrow, here follows the solitary vital, or mortal, fact in the whole business, given in one crushing sentence at the close:—–­

“The medullary tissue” (first time of using this fine phrase for the marrow,—­why can’t he say marrowy tissue—­’tissue moelleuse’?) “appears very early struck with atony,” (’atonic,’ want of tone,) “above all, in its central parts.”  And so ends all he has to say for the present about the marrow! and it never appears to occur to him for a moment, that if indeed the noblest trees live all their lives in a state of healthy and robust paralysis, it is a distinction, hitherto unheard of, between vegetables and animals!

12.  Two pages farther on, however, (p. 45,) we get more about the marrow, and of great interest,—­to this effect, for I must abstract and complete here, instead of translating.

“The marrow itself is surrounded, as the centre of an electric cable is, by its guarding threads—­that is to say, by a number of cords or threads coming between it and the wood, and differing from all others in the tree.

“The entire protecting cylinder composed of them has been called the ‘etui,’ (or needle-case,) of the marrow.  But each of the cords which together form this etui, is itself composed of an almost infinitely delicate thread twisted into a screw, like the common spring of a letter-weigher or a Jack-in-the-box, but of exquisite fineness.”  Upon this, two pages and an elaborate figure are given to these ’trachees’—­tracheas, the French call them,—­and we are never told the measure of them, either in diameter or length,[39] and still less, the use of them!

I collect, however, in my thoughts, what I have learned thus far.

13.  A tree stem, it seems, is a growing thing, cracked outside, because its skin won’t stretch, paralysed inside, because its marrow won’t grow, but which continues the process of its life somehow, by knitted nerves without any nervous energy in them, protected by spiral springs without any spring in them.

Stay—­I am going too fast.  That coiling is perhaps prepared for some kind of uncoiling; and I will try if I can’t learn something about it from some other book—­noticing, as I pause to think where to look, the advantage of our English tongue in its pithy Saxon word, ‘pith,’ separating all our ideas of vegetable structure clearly from animal; while the poor Latin and French must use the entirely inaccurate words ‘medulla’ and ‘moelle’; all, however, concurring in their recognition of a vital power of some essential kind in this white cord of cells:  “Medulla, sive illa vitalis anima est, ante se tendit, longitudinem impellens.” (Pliny, ‘Of the Vine,’ liber X., cap. xxi.) ’Vitalis anima’—­yes—­that I accept; but ’longitudinem impellens,’ I pause at; being not at all clear, yet, myself, about any impulsive power in the pith.[40]