AXILLARV BRANCHING. 473 



exactly in the angle between the leaf-base and the axis, or more on the leaf-base 

 itself, or even on the shoot-axis above it. Not rarely indeed several growing-points 

 of shoots arise in the axil of the leaf, and if the base of the leaf is very broad, as 

 in the Monocotyledons, numerous shoot-buds may arise close to one another, as 

 for example in the case of many bulbs, and the ilowers in the broad bracts of species 

 of Musa. In Dicotyledons with a narrow leaf-insertion, moreover, two, three, four 

 or more growing-points of shoots are often produced one above the other from the 

 interfoliar part which is in process of elongation, as for example in Gleditschia, 

 Aristolochia, and some other woody plants. This regular, production of new growing- 

 points of shoots in the axils of the leaves obtains however, even in the Monocoty- 

 ledons and Dicotyledons, only within the vegetative region : in the inflorescences it 

 is a frequent phenomenon that flowering shoots arise without the previous formation 

 of bracts (Aroidea, Crucifera). Conversely, however, no growing-points of shoots 

 make their appearance in the axils of the foliar structures of the flower itself. The 

 theory of the older morphology which culminated in the establishment of a so-called 

 principle of axillaiy branching, therefore, does not generally obtain even in the 

 Phanerogams with which that morphology was almost exclusively concerned, and 

 this is still less the case with the other classes of plants. If we confine ourselves 

 in the first place to the Coniferse, the nearest related to the Phanerogams, the rule 

 certainly obtains here also that within the vegetative region shoot-buds are produced 

 only in the axils of the leaves, but with the difference that although the leaves are 

 exceedingly numerous, but few of them produce growing-points in their axils : in 

 spite of the copious and magnificent branching of the Coniferae, it is, from the point 

 of view of its development, only sparse in comparison with that of the Monocotyledons 

 and Dicotyledons. In the Vascular Cryptogams, however, and so far as is known in the 

 Muscinese and Algae, the formation of secondary growing-points, or the branching 

 of the vegetative shoot, is entirely unconnected with the axils of the leaves, although 

 the tendency always exists for lateral shoots to make their appearance by the side 

 of or under the insertion of individual leaves. However it would be superfluous 

 for our purpose to treat in greater detail here of the individual cases which have 

 been more exactly investigated. 



We have hitherto confined our attention^ with respect to branching, to the ordinary 

 case, where new growing-points of shoots spring laterally from a growing-point, or 

 from a shoot-axis, or from a leaf-base, the parent growing-point itself continuing 

 to grow undisturbed. Much rarer, and confined to a few small subdivisions of the 

 vegetable kingdom only, is the so-called Dichotomy of the growing-point. We 

 may take as the characteristic distinction of this that the embryonic tissue of a given 

 growing-point obtains two apical points, each of which now constitutes the apex 

 of a new growing-point, and thus the embryonic substance of a growing-point 

 becomes, so to speak, split into two growing-points, situated close beside one 

 another and equal in value. This case is particularly clear where an apical cell 

 exists from which two new apical cells arise, each of which then forms its segments 

 as I have already explained in the previous lecture (cf. Fig. 291). The accompany- 

 ing figure (Fig. 312) may serve to illustrate the branch-system of the same plant, 

 proceeding frorti the dichotomy. It will be observed that a depression occurs at the 

 apex of the shoot, and that the prominences which lie right and left of it grow further 



