TRANSPORT OF CONSTRUCTIVE MATERIALS. 355 



had been conveyed from the organs outside the box to the etiolated shoot inside : 

 the necessary water and ash ingredients coming from the roots, and the organic 

 substance from the green leaves. The fruit alone contained about 250 grams of 

 organic substance, and if we assign to the other etiolated organs in the box — the 

 shoot-axes, leaves and tendrils — the very slight value of 50 grams of organic sub- 

 stance, we have about 300 grams of organic substance, conveyed in the course of 

 seventy-four days from the green leaves into the parts growing in the dark. Up 

 to the ist of September the substance was provided exclusively by the thirteen leaves 

 situated outside the box, and they possessed an assimilating surface of i"5 sq. metres. 

 The shoots which subsequently grew out, beyond the roof of the box, were able to build 

 up their constructive matters themselves: only the water and mineral matters had to 

 be conveyed to them from the roots through a distance of 4-5 metres. If we had 

 made our experiment with the difference that, after conducting the bud into the box, 

 all the leaves outside were cut away, or themselves placed in darkness in the same 

 way, the bud would then have grown in the box for a few days longer, and then all 

 the parts in the dark would have perished. The incidental abnormalities of the 

 organs developed in the dark come no further into consideration here. If during the 

 period of vegetation, however, we had investigated the etiolated organs in the box 

 micro-chemically, we should have found sugar and starch-grains in the parenchyma of 

 the shoot-axes and petioles, proteinaceous matters in the sieve-tubes of the vascular 

 bundles, protoplasm in all the cells, and etiolated yellow chlorophyll-grains in the 

 yellow leaves ^ 



If we now enquire as to the forms of tissue^ in which the plastic substances from 

 the reservoirs of reserve-materials are conveyed to the growing parts, the answer may 

 be given generally that the albuminous matters move in the phloem of the vascular 

 bundles, while starch, sugar and fats, and the nitrogenous substance asparagin, 

 belonging to the protoplasm-formers, are conveyed in the parenchymatous tissues of 

 the shoot-axes, petioles, roots, etc. The materials mentioned may be recognised at 

 all times on these routes, so long as the conditions for so doing exist — i. e. if it is 

 observed whence the matters in question come, and where they are made use of. 

 Apart from a few special cases, it is shown that every portion of an organ about to 

 begin to grow vigorously, becomes in the first place filled with proteid matters (or 

 asparagin), and with fine-grained starch and sugar, which are conveyed to it from 

 the reservoirs of reserve-materials, or from the assimilating leaves. Then, when any 

 particular part of a root, shoot-axis, or leaf, etc. is fully developed, the materials 

 become used up and disappear. 



It is not to be forgotten here, however, that by means of growth itself, the 

 organs already developed come to lie between those parts which supply the materials 



* With respect to the behaviour of plants in the dark, cf. my treatises ' Über den Einßuss des 

 Tageslichtes auf Neubildung und E7itfaltung verschiedener Pflanzenorgatie'' (Bot. Zeitg. 1863), and 

 'Die Wirkung des Lichtes auf die Blut hefibildnng unter Vermittlung der Laiibblättcr' (Bot. Zeitg. 

 1865, No, 15, &c.). 



^ My first publications directed against the old theory of the descending sap are, ' Über die 

 Leitung plastischer Stoffe durch verschiedene Gewebeformenl Flora, 1863 (p. 33), and the chapter on 

 the translocation of plastic substances in my ' Experimental-physiologie' (1865, p. 374\ where the 

 older literature is also cited. 



