ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 71 



numbers found in the parents. The hairs found on both the pitcher 

 and the rim likewise show a blending of the parental characters. 

 Sections of the pitcher, the rim and the lid show that the cell-structure 

 is intermediate in every respect. In all cases where there are apparent 

 variations from exact blending, they are probably due to the higher 

 state of evolution of one of the parents. The writer concludes that 

 such overwhelming evidence of the blending of parental characters 

 ■" points to some exact relation in molecular structure of the hybrid 

 plant, extending even to the amount of thickening laid down in a cell- 

 wall, the size of the starch-grains, or the size of a chloroplast." S. G. 



Ray-tracheid Structure in Second Growth in Sequoia Washing- 

 tonia (S. gigantea).— H. C. Belyea {Bot. Gaz., 1919, 68, 467-73, 

 5. figs.). Ray-tracheid structure is an essential feature of the Coniferales, 



Radial section of second-growth wood, showing wood-tracheid bent 

 and prolonged along the ray to act as ray-tracheid. 



but is only constantly and normally present in the older genera. In 

 the younger genera this structure may or may not be present, but is 

 invariably recalled under traumatic stimulus. The author describes a 

 peculiar adaptation in ray-tracheid structure in the second-growth wood 

 tissue of Sequoia gigantea. Ray-tracheid structures have already been 

 found to occur normally in both species of the genus, S, gigantea and 

 S. virens. In the mature wood of the former two kinds are to be 

 found — namely, single isolated detached radially elongated elements on 

 the upper and lower margins of the primary rays ; and, secondly, inter- 

 spersed ray tracheids occurring in the radial prolongation of rays one 

 cell high. In the present instance sections were taken from the main 

 trunk of a tree which showed a phenomenally rapid growth. In this 

 specimen true ray-tracheids do not occur, but the marginal structures 

 ■on the rays of the wood of second growth show great variation. The 

 vertical wood-tracheids terminate directly at the ray, and there are 



