478 



SCIENCE. 



[Vol. Y., No. 123. 



But Linne did better than this toward the 

 solution of our problem. In his ' Philosophia 

 botanica ' of 1751, he, among other things, 

 makes the following propositions : — 



" Principium florum et foliorum idem est," 



" Principium gemmarum et foliorum idem est," 



which, so far as it goes, would seem a clear 

 statement of the truth ; but it is doubtful 

 whether the author, as he wrote, appreciated 

 the full import of his words. Certainly his 

 immediate followers and pupils did not. He 

 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 pertaining 

 to his theory of prolepsis, — a theory under- 

 stood neither by his contemporaries, his suc- 

 cessors, nor possibly even by himself. 



But while Linne was thus hopelessly lost 

 in the mazes of his own imaginings, another 

 mind, working in an entirely different field, took 

 cognizance of the problem. A young student, 

 afterwards known to fame as Caspar F. 

 Wolff, away in central Germany in Frederick's 

 universit}^ of Halle, had caught the spirit of 

 genuine scientific research, and in his thesis 

 for 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. His taste lay in 

 the line of anatomy in its ordinary scope ; and 

 the reference in his thesis to matters botanical 

 was entirely apart from the chief purpose of 

 his dissertation, simply incidental for the sake 

 of completeness ; and perhaps, with the propo- 

 sitions of Linn6, 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- 

 dinar} T similarity everywhere patent. Regard- 

 ing the involucre of the ' compound ' flower 

 as calyx, he perceived easily the intergradation 

 of foliage and sepals ; the ripened capsule, 

 with bursting sides, afforded evidence of the 

 foliar nature of the carpels ; that the seed is 

 largely made up of leaves, appears when it 

 germinates, and the cotyledons assume and 

 perform, to some extent at least, the leaf's 

 function ; sepals and petals are often inter- 

 convertible, and stamens not infrequently 

 show transition to petals : consequently in 

 the entire plant, so far as immediate analysis 



goes, we find nothing but root, stem, and 

 leaves. 



As Wolff's thesis had to do with generation, 

 and not at all with botany, it is a matter of 

 no surprise that he regarded all this simply as 

 introduction, and went on with his ' theoria 

 generations, ' alleging that the formation of 

 flower and fruit is due to failing energy in the 

 plant ; that all modifications have origin in the 

 gradual withdrawal of vegetative power, which 

 diminishes in amount as growth continues, and 

 finally vanishes altogether. What Wolff hoped 

 might be science, has been forgotten ; what he 

 lightly esteemed, is science, — fact not without 

 significance, and certainly not without parallel 

 in the history of intellectual work. 



But if Wolff did not appreciate what he 

 had accomplished, neither did any of his 

 contemporaries. The seed fell not into good 

 ground. The great Haller was yet living and 

 working, at once botanist, anatomist, and poet ; 

 but he saw not the truth, although certainly 

 familiar with Wolff's writings. The Jussieus 

 were busy in Paris, arranging and re-arran- 

 ging in the Jardin des plantes ; but they heard 

 nothing of Wolff: the time was not } r et. The 

 scientific vision of the age, dazzled by a sud- 

 den discovery of Nature's richness and variety, 

 was not yet ready to be concentrated upon 

 any single problem, however interesting that 

 problem might be in statement, or far-reaching 

 in outcome and solution. T. H. McBride. 



VELOCITY AND SEDIMENT. 



The observations on velocity and sediment 

 on the Mississippi River, from Cairo to the 

 head of the Passes (1,060 miles), have not 

 confirmed the conclusion of Mr. Login, in 

 ' The benefits of irrigation in India,' regarding 

 the relation between these two functions of 

 flowing water. His conclusion is thus stated : 

 ' ' The author believes that the power of water 

 to hold matter in suspension is directly as the 

 velocity, and inversely as the depth. It is also 

 suggested that water in motion rolls rather 

 than slides, and that it is owing to this rotary 

 motion that water has the power to hold mat- 

 ter in suspension ; further, that, with given 

 velocities and defined depths, only a certain 

 quantity of matter can be held in suspension, 

 whatever may be the character of the bed or 

 bank of the river or canal. If the velocity be 

 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- 

 posit." 



