PSEUDO-ENDOGENOUS BUDS. ^ 475 



The formation of new growing-points of shoots in any of the above-mentioned 

 ways constitutes, however, merely the ground-plan of the branch-system which will 

 be ultimately developed, for it is only in rare cases that all the growing-points 

 of shoots which have gradually arisen from one another, and ultimately form 

 the primary shoot of the seedling, come to complete development. Very frequently 

 this happens only in the case of a few, while the others pass over into a dormant 

 condition, either to attain complete development in the next period of vegetation, or 

 to remain unchanged for an indefinite time as the so-called dormant eyes of many 

 forest trees, until by the removal of vigorous shoots opportunity is afforded to 

 them for further development. The sprouting of numerous twigs from the older 

 branches and stems of forest trees when the apical parts have been removed 

 consists in the sudden invigoration of these dormant buds, which have often been 

 developed many years previously when the corresponding part of the stem itself was 

 yet in the condition of a bud. Such dormant eyes must not be confounded with 

 the adventitious shoots to be described subsequently. 



Like the leaves, the new lateral shoots usually arise exogenously, or superficially, 

 so that not only the internal but also the outermost layers of tissue of the growing- 

 point take part in their production, and thus a complete continuity of the systems 

 of tissue is brought about, exactly as in the case of leaves. It was for a long 

 time supposed that the Equisetums formed a peculiar exception to this very general 

 rule. As a matter of fact we find, on cutting longitudinal sections through the 

 buds of the haulms of these plants, the lateral buds situated in the axils of the leaf- 

 sheaths, and completely enveloped by the tissue of the main shoot, much as in the 

 case of roots ; but more exact investigations have shown that this is only due to sub- 

 sequent change, and that, even in the Equisetaceae, the very youngest bud-rudiments, or 

 lateral growing-points, proceed from superficial layers of tissue of the growing-point 

 which gives rise to them. The matter is very similar, though more complicated, in 

 the case of the two trees Symphoricarpus and Gle.ditschia, much cultivated in our 

 gardens. We may say a few words with respect to Gleditschia : the thorns on the 

 leaf-shoots are the original, axillary shoots of the leaves, but by the growth of the 

 mother-axis they become pushed some distance upwards from the axil of the leaf. 

 A series of further buds then arise progressively towards the axil of the leaf, the 

 embryonic tissue at the axil evidently persisting as such for a long time. These 

 later buds remain very small at first, and, as Hansen established, become so 

 enveloped and overgrown by the cortex of the mother-shoot during the current period 

 of vegetation, that when they begin to sprout in the following spring it looks as if they 

 had been produced in the interior of the cortex which they then break through. 

 As the biology of plants everywhere affords thousands of examples of the fact that 

 young buds are preserved for future periods of vegetation, and protected and 

 enveloped in the most various ways, so we find even in some woody plants (e. g. 

 Virgilia luted) that the broad base of the leaf encircles its axillary bud so completely 

 that nothing at all is to be seen of it from without, and it only comes into view after 

 the removal of the leaf-stalk. 



In contrast to all these various cases of an only apparently endogenous origin 

 of shoot-buds, it appears however that flowers and inflorescences may arise in the 

 interior of previously more or less amorphous masses of tissue, particularly in the case 



