338 Anatomie. 



of the development of centripetal wood. The following observations 

 support this conclusion: 



1. There is no correlation between the amounts of the two 

 tissues, but more transfusion elements are present in the largest 

 cotjrledons and in those which retain their assimilatory functions 

 for the greatest length of time. 



2. The size of the transfusion tracheids differs greatly from 

 that of the xylem and usually the smallest elements are those nearest 

 to that tissue. 



3. The transfusion tissue is never more abundant on the adaxial 

 side of the bündle and usually not more than one element is found 

 there. At least one layer of parenchyma separates it from the xylem 

 when it does appear on the ventral side. 



Some experiments were performed to throw light as to the 

 function of the tissue, but the question as to whether it serves for 

 conduction or for storage was not conclusively settled. 



E. de Fraine. 



Compton, R. H.. The Anatom y oftheMummyPea. (New 

 Phyt. X. p. 249-255. 4 textfig. 1911.) 



The Mummy Pea is a variety of Pisnm sativum in which the 

 abnormal appearance is due to fasciation. The main axis is distended 

 at the apex and is funnel shaped, but the tip is open so that the 

 whole cavity of the dilated portion is open to the external air. 



The structure of the lowest internodes is normal for the Vicieae, 

 and has "medullary" xylem and extra-stelar, stipular bundles, this 

 gives place higher up to the development of a fistular pith and a 

 ring of collateral vascular bundles. In the upper region of the 

 swollen, funnel-shaped axis there is a second ring of bundles, in- 

 ternal to the first, in which the orientation of the tissues is reversed; 

 the central cavity is limited by an epidermis with cuticle and sto- 

 mata. The tissue between the two series ol bundles becomes fistular 

 when the stem reaches a certain age so that the two rings of vas- 

 cular tissue become separated and the inner portion hangs freely in 

 a space, being attached, however, at the slender tip in the region 

 of a leaf-node. There are now vascular connections between the 

 inner and outer rings. The whole internal complex of tissue could 

 function independently of the rest of the plant, its existence is, 

 however, probably only the expression of some morphological 

 determination. 



The structure belongs to the class of abnormalities known as 

 ring-fasciations, and its produced in the Mummy Pea by the method 

 of direct tubulisation, in other examples it may be the result of 

 invagination of the external tissues. The Suggestion is put forward 

 that the medullation of the stele in Pteridophyta, Pteridospermae 

 etc. may, like ring-fasciations, arise in different ways; either by 

 direct tubulisation, i.e. the intra-stelar method, or by invagination, 

 i. e. the extra-stelar method. E. de Fraine. 



Gram Bille. Til Belysning afHypoderm-Funktioner. (On 

 the functions of hypodermas). (Biol. Arb. tilegn. Eug. War- 

 ming. Köbenhavn 3 Nov. 1911. p. 217—230. 5 fig.) 



The matter contained in the cells of different hypodermas was 

 examined partly in sections bj r microchemical reagents and partly 

 by chemical analysis; details are here omitted. In combining these 



