Anatomie. 227 



of various workers and nuraerous examples are given to illustrate 

 the point. 



Resin canals arise, not as structures of a primary nature, but 

 from the tearing apart of these cell aggregates to afford an inter- 

 cellular passage; numerous instances are given in support of this 

 view, which is also borne out by the fact that the largest number 

 of canals occur in the regions where food is most abundant, that 

 they diminish or are absent in specimens of weak growth. Evidence 

 is given to shew that structurally the vertical parenchyma aggre- 

 gates and the raedullary rays are similar; their function , the con- 

 duction and storage of elaborated food stuffs, is the same. The 

 intercellular Spaces which appear in them are part of the aerating 

 System, and the resin they contain results from the efforts of the 

 active epithelial cells to get rid of excreta; this is supported by the 

 fact that the resin canals are never a continuous System. 



Jeffrey's views on traumatic resin canals are fuUy discussed, 

 the author concluding that "the reversion theory" is unsatisfactory, 

 but "that the traumatic appearance of the so-called resin canals is 

 due to the same general causes as those which call forth the nor- 

 mal formations of these structures in other species." 



Observations made on thyloses in Conifers confirm the conclu- 

 sions arrived at in the case of Pteridophytes, and the general 

 rules governing thyloses whenever and wherever they appear are 

 given. E. de Fraine. 



Lee, D. G., Notes on the Anatomy and Morphology of 

 Pachypodium namaquanum, Welw. (Ann. Bot. XXVI. 103. p. 

 929-941. 1 PI. 8 textfig. July 1912.) 



The habit and habitat of this curious member of the Apocynaceae 

 is described. The stero is covered with fleshy protuberances'arran- 

 ged in a close spiral, each protuberance ending in three, hard, 

 Sharp, spines. The young protuberance arises in the axil of a leaf , 

 but subsequent basal growth results in the leaf scar being carried 

 up laier. 



The anatomy of the stem is described; its chief feature is the 

 possession of a bulky and complex pith, increase in the size of 

 which occurs by the irregulär division of its cells. This pith largely 

 consists of water storing parenchyma, but it contains a complex of 

 branching and anastomosing meduUary bundles of varied size and 

 orientation, and also numerous laticiferous elements. It is suggested 

 that these meduUary bundles, of which the origin could not be 

 determined, represent the intraxylary phloem characteristic of the 

 Order, but that xylem is present in addition to the phloem. 



Details are given with regard to the structure of the protube- 

 rances, spines and leaves. The morphology of the protuberances 

 and spines is discussed and the author concludes that two serial 

 axillary buds occur in the axil of the adnate leaf; the Upper gives 

 rise to the inflorescence, the vascular supply of which is derived 

 from the vascular ring of the stem; the lower is the apex of the 

 protuberance which receives its bundles from the meduUary region 

 only. The Suggestion is made that the median spine is best regar- 

 ded as a stem spine, the two laterals as modified leaves; their 

 function is probably water storage for the use of the inflorescence, 

 while they serve later to reflect intense sunlight from the stem. 



E. de Fraine 



