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der or ring of primary bundles." In his opinion it is the need 

 of storage tissues, in particular around the leaf-traces, which has 

 occasioned the formation of aggregate and compound rays. 



This need for storage tissues was connected with changes 

 of temperature at different times of the year. With respect to these 

 rays he further writes: "By gradual development of the amount 

 of special storage tissue, above and below the traces, and its ex- 

 tension outward with each annual layer of growth, a larger and lar- 

 ger food-reserve system has been developed, until in the higher 

 types, by the transformation of the compounding tissue, con- 

 sisting of aggregated small rays and separating fibres into ray pa- 

 renchyma, homogenous masses of ray tissue have been produced". 



It is really impossible to decide pro or contra in this question, 

 nor is it clear, what meaning broad rays in the annual rings out- 

 side the first ring can have for the formation of separate vascular 

 bundles in annual, herbaceous stems. Referring to the structure 

 of the stem in species of Quercus he seems to be the victim of a 

 misunderstanding. It is wrong when he means that, according to 

 the hypothesis of Sachs and de Bary, five fascicular bundles should 

 be found here and between these five interfascicular bundles. In 

 Quercus pedunculata at least, no interfascicular xylem is found, 

 all the bundles being developed in the earlier stages and all passing 

 into the leaves (40 bundles, composed of 5 groups with 8 in each). 



When he with respect to Alnus tenuifolia suggests that this 

 species in its earlier stages has a continuous woody cylinder with 

 unbroken protoxylem, a mistake undoubtedly has taken place. 



In a paper: "The evolutionary history of the foliar ray in 

 the wood of Dicotyledons", occasioned by the criticism of P. Groom, 

 Bailey repeats the main points of this view. Yet he admits that 

 in many cases in more recent dicotyledonous families the broad 

 rays are displaced by narrower. A similar view has been communi- 

 cated by W. P. Thompson in a paper (1911): "On the origin of 

 the multiseriate ray of the Dicotyledons". In his opinion the uni- 

 seriate rays are the oldest, the broad ones being formed by a pro- 

 cess of compounding, first around the leaf-trace and thence through 

 the wood. 



Starting from this stage two ways of evolution are open. "On 

 the one hand the continued development of the compound ray at 

 at the expense of the woody cylinder has resulted in the ultimate 

 production of the herbaceous condition. On the other hand the 



