590 SUMMARY OF CURRENT RESEARCHES RELATING TO 



ture correspondiiig to variation in conditions of growth. At the margins 

 of the rays are tracheitis communicating with the adjacent xylem- 

 bracheids by means of bordered pits. The main part of the ray is com- 

 posed of parenchyma cells, with semi-bordered pits on their lateral walls 

 and simple pits on their end walls. These cells serve for the conduc- 

 tion and storage of the products of assimilation. More complex rays have 

 a third kind of tissue for the secretion, conduction, and storage of resin. 

 The rays have direct communication with the phloem and cambium 

 on the one hand, and the xylem-tracheids on the other, and probably 

 continue their activity as long as the wood performs its physiological 

 functions. The pits formed where the storage-cells are in contact 

 with the xylem-tracheids - show variations related to the life-conditions 

 of the species. In Larix the entire foliage is deciduous each year, so 

 that there is a great demand upon storage-tissue such as is found in the 

 medullary rays. In Picea the leaves persist from four to seveu years, so 

 that there is little, if any, demand upon the storage-tissues. Correspond- 

 ing to this difference, it is found that while Picea has little or no 

 starch in its woody tissues, the ray-tissues of Larix are rich in starch ; 

 this is forced into the tracheids and conveyed to new shoots at the 

 beginning of each new season. The annual occurrence of this temporary 

 current is accompanied by a well-defined increase in the size of the 

 immature, semi-bordered pits, " corresponding to the probable time, in- 

 tensity and duration of the demand " made upon the reserve stores. The 

 structure of the medullary rays of Picea is in all respects similar to that 

 of Larix, but there is no variation in the size of the semi -bordered pits. 

 so that it would appear that the variation in Larix is entirely due to a 

 difference in the conditions of °rowth. 



Reproductive. 



Male Flower of Williamsonia.* — H. H. Thomas publishes an 

 account of the male flower of Williamsonia gigas. The specimen de- 

 scribed belongs to the Yates Collection in Paris, but was found in the 

 neighbourhood of Whitby. It is urn-shaped, and appears to have been 

 composed of eighteen to twenty microsporophvlls 7-8 mm. wide, united 

 below to form a cup-like structure 5-<i cm. wide, with a distinct rim 

 round the edge. The base of the cup tapers considerably to what is 

 apparently a stalk about 1 cm. thick. Down the centre of each sporo- 

 phyll is a series of reniforni or elliptical depressions : the upper portions 

 are indistinct, but appear to have tapered up for about 2-3 cm., and 

 there are indications that branches were given off towards the centre of 

 the flower. The synangia seem to have resembled those of IF. spcctabilis. 

 The classification of the specimen presents little difficulty. There is no 

 doubt as to its generic position, and while no direct evidence is available 

 as to its species, several considerations, especially the fact that it comes 

 from a bed containing stems, leaves and female flowers of W. gigas, 

 point to its being the hitherto unknown male flower of this species. 

 The position and mode of growth are homologous with those of W. specta- 



* Proc. Camb. Phil. Soc, xviii. 3 (1915) pp. 105-10 (1 pi. and 3 figs J 



