January. 1911. 



KNOWLEDGE. 



15 



of magniticent weapons of War and the Chase from 

 the principal river gravels, these paleoliths are seldom 

 shewn ? It is almost a certainty that they occur 

 evervwhere, but owing to the fact that workmen are 

 onlv paid and encouraged to look for the larger 

 specimens, presumabh' the\- are generally overlooked. 

 Secondlv : These small fabrications are not to he 

 found in the later gravels, as in the case of Dover- 

 court, abo\e the clay band, nor are they found 

 associated with large early Neolithic implements of 

 Cisburv and Eastbourne. This seems to point to 

 one of two conclusions, either that side-pressure 

 flaking or "nicking" became a lost art at one early 

 period and was not resuscitated till later Neolithic 

 times: or that the workers (possibly a special race) 



of so-called "pigmy" implements and small side 

 work generally were driven from districts where 

 their ancestors made these "industrial tools," as 

 Rutot so aptly describes them, an;' did not again 

 migrate to the same places for many ":s later. 



Thirdh-: I would suggest more h,^ ; would be 

 thrown on the present mystery of pati/vlion, if a 

 general system were adopted of classing tiu' various 

 implements in all the gravels of England according 

 to their forms and respective ages : and the gaps in 

 the evolution of man's handiwork and arts would be 

 more tilled up by such a system than at present. 



In the accompan\ing illustrations the finds of the 

 two pits respectively are shown in types, and with 

 the name of the pit in which each was found. 



THE MYSTERY OF THE FLORAL PIGAH^XTS. 

 Bv P. O. KEEGAN. LL.D. 



Thk literature on the subject of the colours of flowers has 

 been very voluminous as respects the final cause of the 

 phenomena, but a truly scientific explanation thereof has 

 seldom been attempted. We do not want to disco\er the 

 purpose which these lo\ely pigments fulfil in the economy of 

 the plant, so much as the chemical and physiological efficient 

 causes of their appearance. The chemistry of plants requires 

 to be studied, and the products of the physiological processes 

 going on in their interior need careful detection and distin- 

 guishment. In this way only can the laws which go\ern the 

 vital activity be discovered, and thereby also a true scientific 

 understanding of the phenomena be attained. The corolla is 

 the organ wherein the yellow, blue, and red colouring matters 

 are chiefly produced, and hence its physiology has to be 

 carefully studied and determined, not only in itself, but also 

 in its relationship with that of its neigbouring organs, viz., the 

 stamens and pistils. We know that the corolla grows \ery 

 rapidly, that it is the seat of energetic oxidation and at times 

 considerable transpiration : its assimilatory power is generally 

 feeble, and it has a poor de\elopment of the vascular system, 

 i.e.. of the conducting apparatus. Hence the appearance of 

 the pigments in the corolla has been explained in a general 

 and rather vague way by simple modifications in the phenomena 

 of cellular nutrition and of cellular chemistry (Curtel" ). 

 Chlorophyll is not produced or regenerated in the corolla 

 owing to insufficient nutrition, and hence carotin (the pigment 

 of the orange and deep yellow flowers) is allowed to appear, 

 while the blue and red pigments are due to the energetic 

 oxidation of which this organ is the special seat. This 

 explanation seems to account fairly well for the production of 

 the yellow pigment (carotin), but it fails to throw light on the 

 fact that the red and blue pigments (anthocyan) are e\idently 

 evolved by a verj' special physiological process, which does 

 not generally take place in an\' other part of the plant with a 

 strength and completion at all comparable with that proceeding 

 in the tissues of the corolla. The mere oxidation of an organ 

 is not sufficient, unless something is produced there indepen- 

 dently, whereon the oxidation may operate. If the corolla 

 possesses a very feeble or annulled assimilatory power, its 

 protoplasm exhibits a very energetic deassimilatory power, 

 and this latter fact is proved to demonstration when the 

 chemical constituents of the floral parts are compared with 

 those of the other organs of the same plant. 



A series of chemical analyses of common plants performed 

 by myself (see The Xaturalist, 1902-10). revealed the 

 important fact that, while the flowers of certain species are 

 habitually tinted purely and \ividly. the quantity of tannic 



chrcmogen contained in the other organs (stem, leaf, root) is 

 or may be, extremely small. Hence, the conclusion was 

 readily suggested that the formation and development of the 

 blue and red pigments in these cases were strictly local, and 

 absolutely confined to the floral envelopes, i.e., they were not 

 necessarily dependent on the particular amount of tannin 

 produced by the organism in its entirety. Now, as tannin is 

 a product of deassimilation of a high grade, it seemed certain 

 that this particular physiological process was carried on in the 

 corolla \ery energetically ; it was pushed further there, as it 

 were, than in the other organs of the plant. The question 

 then to be decided was in what manner did it act. and what also 

 were the real causes of its specific energy and completeness. 



It became clear that it was not (as M. Curtel opined) 

 merelv because the corolla possessed feeble powers of 

 assimilation, that, therefore, its powers of deassimilation should 

 be raised correspondingly. The law of plant physiokvgy 

 applicable to this case is that processes of special deassimila- 

 tion are brought about in certain cells to the profit and benefit 

 of other neighbouring cells. The albuminoids of the corolla 

 cells minister to the pressing needs of the stamens and 

 pistils. The vital activity incident to the process of 

 fecundation, the formation and diflerentialion of the stamens, 

 ovules and seeds, etc., induces a powerful drain on the 

 albuminoids of the corolla, whose molecules consequently 

 break up ; the nitrogenous nuclei thereof are separated and 

 pass over as much as is required to the cells of the stamen 

 and pistil, while the aromatic nuclei remain behind as tannic 

 chromogen, the precursor of the brilliant blue and red 

 pigments. Numerous experiments performed by myself (see 

 Xnfiire, Ixi., 1051 render it certain that the conversion of 

 tannin into visible pigment varies in intensity and completeness 

 very considerably, according to the particular petal examined. 

 In cranesbill. tufted vetch, peony, and sweet pea the conversion 

 is complete ; in foxglove, carnation, and some roses it is nearly 

 so; in clover, sea pink, and flowering currant it is not 

 complete : while poppy, burnet and cineraria are still further 

 remote from perfect development of tincture. And, inasmuch 

 as difterent species of plants belonging to the same genus 

 evolve habitually either blue or red flowers, while the 

 chromogen of all is exactly the same substance, there can be 

 no doubt that these diff'erences can only be explained by a 

 diversity in the development of the pigment. As already 

 suggested, the most developed in this respect are those plants 

 which habitually e\olve blue or purplish-blue petals, and it is 

 these very plants which exhibit the most intense and energetic 

 reproductive capacity. 



Annales dcs Sciences Xatiirclles.— Bot. Ser. 8, t. 6, page 221. 



