May 15, 1903.] 



SCIENCE. 



795 



elements are in excess. K the minima of all 

 mineral elements are presented to the plant 

 at the same time, normal growth can not take 

 place. 



In the experiments of "Wolff it was conclu- 

 sively shown that in such' cases flowering and 

 fruiting are practically prevented. The plant 

 has, therefore, need of an excess of mineral 

 matter, and this is secured from other mineral 

 substances if one of the essential minerals is 

 present in a minimum quantity. Thus some 

 mineral foods may, temporarily at least, act 

 as substitutes to a certain degree for others. 

 Strange to say, however, sodium, which is so 

 near potassium in its general properties, has 

 but slight, if any, suitability as a substitute 

 therefor. It is a mistake, therefore, to look 

 upon the constitutional assimilation of min- 

 eral matters as their chief utility. The fact 

 that both potash and phosphorus are always 

 associated with the functions of the living 

 cell is not to be forgotten. The absence of 

 either of these minerals makes vegetable 

 growth impossible. Especially are these two 

 substances the katalytic agents whereby the 

 living cell converts the other mineral foods 

 of plants into starch, sugar, cellulose, oil and 

 protein, of which the organic parts of plants 

 are chiefly composed. These elements reach 

 the tree solely through the soil, and the greater 

 or less abundance of them in the soil can not 

 fail to affect profoundly forest growth, per- 

 haps to a greater extent than almost any other 

 factor of the environment. 



The soil has, therefore, marked ecological 

 as well as physiological influences on forest 

 growth. The soil of the forest is nature's 

 own handiwork and will never be modified by 

 man. When man begins his work the forest 

 ends and the park begins. We all know how 

 the soil alone has, in many instances, deter- 

 mined the character of tree growth. It is not 

 wholly accidental that the sands are covered 

 by pines and the mountains by oaks. The 

 virgin forests in many localities were indexes 

 whereby the early settlers selected their en- 

 tries of land. They did not need to be told 

 that the maple, the walnut and the tulip grew 

 on the richer, and the beech, the gum and the 

 oak on the poorer soils. The first forests that 



fell before the ax were those of the first-named 

 trees. Thus the nature of the soil has often 

 determined the original distribution of forest 

 growth. Nature seems to know the edaphic 

 principle in ecology better than man. 



It is to be regretted that at this late day 

 we should be told by such an eminent author- 

 ity : * Moreover, the total amount of mineral 

 constituents in a tree is not only very small, 

 but by far the, largest portion is found in the 

 leaves and young parts, suggesting again their 

 merely fortuitous presence as a residue of the 

 transpiration current, and mostly not re- 

 quired.' 



I need hardly add the observation that the 

 presence of mineral substances, both as such 

 and as salts of the organic acids, profoundly 

 modifies osmotic pressure, and without the 

 aid of these substances the ' transpiration 

 current ' would never reach the tips of the 

 trees, but, like the vanishing stream of the 

 desert, be forever lost. The incidental fact 

 of peripheral accumulation of mineral matter 

 due to transpiration seems, to have no bearing 

 on the previous utility of the accumulated 

 material during its passage through the cel- 

 lular substance of the tree. 



H. W. Wiley. 



ARE STAMENS AND PISTILS SEXUAL ORGANS? 



In Science, XVII.,' 652, Professor W. F. 

 Ganong suggests that stamens and pistils are 

 sexual organs, and gives some interesting rea- 

 sons for this conclusion. In brief, he proposes 

 to abandon the morphological point of view 

 and adopt one purely physiological. It must 

 be admitted that a genuine argument is pre- 

 sented here, but it is still open to question 

 whether such a use of terms conduces to clear- 

 ness. If the stamens are male organs, I sup- 

 pose their product, the pollen spores, must be 

 regarded as male cells. And if the pistil is a 

 female organ, I suppose the scattering of 

 pollen spores upon the stigma must, if one is 

 consistent, be considered as a sexual act and, 

 in that case, may be termed, as Mueller did, 

 ' Befruchtung.' But to the mind of a mor- 

 phologist this confusion of the processes of 

 pollination and fecundation is extremely ob- 



