December 1, 1888,] 



THE GARDENERS' CHRONICLE. 



633 



plants it would appear that in some starch is nnt 

 found at all, some other carbon compound instead 

 being present. 



Sachs, writing in 1882, claims that he was the 

 earliest investigator to lay down that the first defi- 

 nitely established product of assimilation is starch. 

 He says that in 1862 he came to the conclusion that 

 the enclosed starch, which had been observed in the 

 chlorophyll corpuscles by Nageli and Mohl, is to be 

 regarded as the first evident product of assimilation 

 formed by the decomposition of carbonic acid, and 

 gives references to his papers of 1862 in Flora und 

 Botanisehe Zcitung. He points out that the action in 

 a leaf is local. By placing one-half of a leaf in 



B C D 



in the leaves is perhaps of secondary importance. 

 The paper (of which an abstract has been given in 

 English) is, however, of interest, since among other 

 things it gives a description of the method of study- 

 ing the chemical effect of light on cells with the 

 help of the microscope. The plates show, magnified 

 700 or 800 times, the appearances of the cells as 

 chemical changes occur in them, and he especially 

 points out the care he took that the effects of heat 

 and of light should not be confounded. Though he 

 speaks of the relation between the action of chlo- 

 rophyll and the formation of carbon compounds 

 being wholly hypothetical, and not supported by 

 experiment, it may be noted that Sachs, who has 



FlO. 89, — SPECTRA OF CHLOROPHYLL. 



FlO. 90. — DECOMPOSITION OF CARBONIC ACID, AND ASSIMILATION OF CARBON. 



Dotted lino = heat; tine line ** brightness; thick line = nssimilntioi 

 furbig&n Lickte auf die Zersetznng der KbhlmsSure in Pfl tn:e 

 Wur.burg," ISM. 



From a paper by W. Pfeffer, Die Wirhmg 

 p. 46, bi. i., "Arbeiten des Bot. Inst, in 



atmosphere deprived of carbonic acid, while the 

 other half is in ordinary atmosphere, there is no 

 starch formed in the first half, while in the second 

 there is. Similarly, if a portion of a leaf is shielded 

 from light action, no starch formation takes place 

 there. This limits the question of starch formation 

 to the action of individual cells, and reduces the 

 study of this part of the question to the action of 

 light and decomposition of carbonic acid in each 

 cell. 



Pringsheim, however, in a lengthy paper published 

 in Leipzic, 1881, urged that hypochlorin is the 

 primary product of assimilation resulting from de- 

 composition of carbonic acid. To the cultivator 

 whose chief consideration is the formation of starch 

 in the tuber, the question of details of its formation 



since written, maintains that starch is the first 

 visible product. 



With regard to the chlorophyll itself, researches 

 with the spectroscope have shown that it is probably 

 not so simple a body as was at first proposed. 



Fig. 89 gives the spectrum (a) of the extract of 

 green leaves obtained by their solution in alcohol ; (b) 

 of the blue constituent, which is soluble in benzol ; 

 and (c) of the yellow constituent. The letters refer 

 to the position of the lines (known as Fraunhofer's) 

 so commonly used in mapping spectra, and the 

 figures to Kraus' absorption bands. 



But whatever may be the outcome of present re- 

 search, the fact seems well established that the 

 action of light with chlorophyll is essential to the 

 formation of starch, and, further, that light which is 



intense enough to produce the green colouring 

 matter of plants, is not necessarily enough to affect 

 the decomposition of carbonic acid followed by for- 

 mation of starch. It would be an interesting point 

 to know the relative amount of starch-forming work 

 effected by Potato leaves fully exposed, and by those 

 shaded by others, as this might be found to point to 

 the value or not of full-foliage plants. 



The kind of light, or " part of the spectrum," which 

 has the greatest influence on the decomposition of 

 carbonic acid and assimilation of carbon, has been 

 studied by Draper and by Pfeffer.* Pfeffer hts 

 represented the results of his researches by a diagram 

 (fig. 90). a. is the band at the red end of the 

 spectrum, and the letters follow to h in the violtt 

 end. The figures 1, 2, 3, are in the " infra red." 

 The height of the thick line shows the varying 

 amount of assimilation, and it will be seen that its 

 maximum is between d and e, where the yellow and 

 blue of the spectrum begin to mingle into green. 

 ( hitside c and r the effects are but slight. In 

 experiments with artificial cultivations, or in grow- 

 ing under tinted glass, such knowledge is of import- 

 ance. 



The method of development of starch-grains has 

 been carefully studied by A. F. W. Schimper.t Even 

 for those who would not trouble to read the paper 

 the plate is of interest. But in no illustration does 

 he refer to the Potato. He does, however, in passing, 

 mention starch grains in the stem of the Potato. 



Amid all the activity of work it seems strange 

 that with our Potato crops, second in importance only 

 to our cereals, the study of the formation of tubeis 

 is practically untouched. Beautiful Potatos may 

 be met with at shows ; at certain places good table 

 Potatos may be purchased; but our general market 

 supply is certainly not so good but that it might be 

 improved. IV. S. M. 



(To be concluded.) 



The Apiary. 



Beekeepers will again need reminding that, 

 winter coming upon us, the long evenings may be 

 usefully employed in reading up the subject, though 

 books without practice is not advocated. 



The month has been stormy generally, but the 

 weather has been mild, and bees have had a great 

 many flights. This is good for them, but as a con- 

 sequence there is an immense demand on the stores, 

 and woe betide the man who has not fed his bees ! 

 I know a cottager who acts on the " let 'em alone ' 

 system. Already he has about thirty stocks out of 

 fifty dead. It is absolute nonsense to let them 

 alone. If fodder were scarce would the farmer 

 starve his cows ? It is too late now to give liquid 

 food, but candy may be put under the quilt just 

 over the cluster, and this will save many a stock. 

 Entrances may now be opened to their full width, as 

 all danger of robbing may be considered at an end 

 till spring, and air is beneficial to the hive in assist- 

 ing to keep it dry. The bees should not be dis- 

 turbed unless they a<-e starving, and then only as 

 above directed. If it is necessary to move hives, it 

 had better be postponed till the bees are absolutely 

 gone to rest. That will be in about another month. 

 See. 



EXPERIMENTS IN HYBRIDIS- 

 ING BARLEY. \ 



The author stated the results he has obtained by 

 crossing Hordeum vulgare, H. hexastichum, H. di- 

 stichum, H. Zeocriton, and H.trifurcatum, as made by 

 him since 1884 on a large scale. He illustrates his 

 subject with specimens. He described the precau- 

 tions to be taken in such crossing experiments, and 

 deduced the following conclusions : — (1), All the 



* Draper. Ann. da Cheinie ct de physique, 1814. p. 214. &e. 



t Hot. Ztit., No. 62, 1880; Traii-l. in (j. J. Mic. Set., 1881, 

 p. 991, with plate xix. 



J By M. Beyerinck ! before Rjyal Academy of Sciences, 

 Amsterdam, Holland, June : 



