I
��But Linn^ did better than tbis toward the solution or our problem. In hia ■ Philosophia botatiica' of 1751, lie, aiuoog other tilings, makes the following propositions : —
1 idem est,"
which, so far as it goes, wouid seem a clear statement of the truth ; but it is doubtful whether the author, as be wrote, appreciated the full import of his words. Certainly his immediate followers and pupils did not. lie stood face to face with the truth, but recog- nized it not, and turned away from it. and from the only line of thought which could pos- sibly lead to light, only henceforth to wander in vain speculations and obscurities jiertaining to hia theorj- of prolepsis, — a theory under- stood neitber by bis contemporaries, bis suc- cessors, nor possibly even by bimsetf.
But white Linn^ was thus hopelessly lost in the mazes of his own imaginings, another mind, working in an en tirelj' different field, took cc^nizance of the problem. A young student, afterwards known to fame as Caspar F. Wolff, away iu central Germany in Frederick's universily of Halle, had caugbt the spirit of genuine scientific research, and in his tbesis tor graduation in 1759 published an exact, succinct, and perfectly clear statement of the modern doctrine of vegetable morphology. Wolff had ideas of his own concerning genera- tion in all the organic world, more particularly in the world of animal life. Hia taste lay in the line of anatomy in its ordinarj- scope ; and the reference in his tbesis to matters botanical was entirely apart from the chief purpose of bis dissertation, simply incidental for the sake of completeness ; and perhaps, with the propo- sitions of Linn^, above cited, before him, he had no thought of propounding any thing new to botanical science. In perfect harmony with his subject, Wolff undertook to elucidate the origin of the various organs of a plant, and in so doing was struck with the extraor- dinary similarity everywhere patent. Regarding the involucre of the ' compound ' flower as calyx, he perceived easily the intergradation of foliage and sepals; the ri|>ened capsule, with bursting sides, afforded evidence of the foliar nature of the carpels t that the seed is lat^ely made up of leaves, appears when it germinates, and the cotyledons assume and perform, to some extent at least, the leafs fiinetion ; sepals and petals are often inter- convertible, and stamens not infrequentlj' show transition to petals : consequently in the entire plant, so far as immediate analysis
���tVOL. T.
��Thopeit what h^^
withjH
'hat B^*
���goes, we Sad nothing but root. stem, i leaves.
As Wolffs thesis had to do with generation, and not at all with botany, it is a mutter of no surprise that he regarded all this simply ns introduction, and went on with his ■ theoris generationis.' alleging that the formation of flower and fruit is due to failing enero;y in the plant ; that all modifications have ori^n in the gradual withdrawal of vegetative power, which diminishes in amount as growth continues, and finally vanishes altogether. What Wolff hopeil migbt be science, has been forgotten ; w' " ' lightly esteemed, is science, — fact not w significance, and certainly not without \ in the history of intellectual work.
But if Wolff did not appreciate what 1 had accomplished, neither did any of his contenijjorarics. The seed fell not into good ground. The great Haller was jet living and working, at once botanist, anatomist, and poet ; but he saw not the truth, although certainly familiar with Wolff's writings. Tbe Jussieus were busy in Paris, arranging and re-arrau- ging in the Jardin des plantes ; but they heaid nothing of Wolff: the time was not yet. The scientific vision of the age, dazzled by a sud- den discovery of Nature's richness and var" was not yet ready to be concentrated ; any single problem, however interesting t problem might be in statement, or far-reacli in outcome and solution. T. H. McBbidb^
��VELOCTTY AND SEDIMENT. The observations on velocity and sedin . on the Mississippi River, from Cairo to 1 head of the Passes (1,U60 miles), have i confirmed the conclusion of Mr. Login, 1 ' The benefits of irrigation iu India.' reg^r^ the relation between these two functions | flowing water. His conclusion is thus sU " The author believes that the power or i._, to hold matter in suspension is dircctl}' as I velocity, and inversely as the depth. Hi ' suggested that water in motion rolls than slides, and that it is owing to this roUJ motion that water has the power to hold i_ ter in suspension ; ftirtber, that, with giJ velocities and deOned depths, only a cert quantity of matter can be held in suspensi whatever may be the character of the bed^ bank of the river or canal. If the velocity B_ increased, and the depth remain constant, scour will take place. If the velocity be decreased, and the depth is the same, there will be de-
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