1909] CURRENT LITERATURE 171 



which are briefly as follows: Contrary to Fitting's conclusion, in a combination 

 of the rest position with various angles, the statolith starch takes the position that 

 would be expected by the statolith theory. Centrifugal acceleration causes the 

 movement of the starch that the hypothesis assumes, as shown by accelerations 

 from 0. 13 g to 9 g. In these various accelerations the time of the movement of 

 the starch to the side of the cells coincides with the presentation time as deter- 

 mined by Bach. In the intermittent exposures of opposite sides when these 

 exposures are of short duration the starch moves to the side of the cell of the 

 most effective exposure only after the process is long continued, corresponding to 

 the slow reaction in these cases. However well this paper may answer a number 

 of the arguments against the statolith theory, there are yet a number unanswered 

 and this whole matter of geotropic reaction seems too complex to be entirely 

 explained in such a simple way.— Wm. Crocker. 



Ray-tracheids in Cunninghamia.— The complex structure of the medullary 

 rays of living Abietineae, consisting of parenchyma cells, ray-tracheids, and an 

 elaborate system of ligneous resin-canals, has been used as one of the evidences 

 of a highly specialized and relatively modern group. Jeffrey 2 ? has studied the 

 marginal ray-tracheids that occur occasionally in Cunninghamia and has found 

 iem to be due to wounding, being most numerous in the region of the injured 

 annual rings opposits the wound-callus. They resemble in general those de- 

 scribed for certain genera of the Taxodineae and Cupressineae, and Jeffrey 

 thinks that this is additional evidence that these two tribes have been derived from 

 «e Abietineae, the ray-tracheids being "vestigial or reversionary." He emphasizes 

 t is view by calling attention to the fact that there is no evidence that the Taxo- 

 toeae and Cupressineae existed before the end of the Cretaceous. Such conclu- 

 sions illustrate the fact that apparent simplicity of structure may not indicate 

 ^ater antiquity than greater complexity of structure.— J. M. C. 



VaSC " Iar s y stem of Ranales.— Worsdell 28 maintains that the primitive angio- 

 L d lar S e leaves > and that as a result the vascular bundles were disposed 



ii]cre SCaUered manner, as is seen in the monocotyledons. He considers that 

 split 6 'VY 11 CaSeS a Sbgle terminal cotyledon in the embryo, but that it may 

 term* i haUeS diverge throu g h l8o °- Like the cotyledon, all the leaves are 

 condit t rganS ' and henCe dominate the stem ("grandifoliate"). *™ m this 



small T bCen derived the one in which the stem is dominant and the leaVCS 

 reject l th PamfoIiate "). This view of phylogeny naturally leads Worsdell to 



Jeffrey* CVldence derive d from the vascular system of seedlings adduced by 

 In the and ° therS ' althou g h he claims to adopt the "recapitulation theory." 

 P^sent paper he outlines the results of an extensive study of the leaves in 



27 T 



Aniuus oM^' Edward C -» Traumatic ray-tracheids in Cunninghamia sinensis. 



***** »:S9**». * jr. X908. 



^nales J°^> W - C -. A study of the vascular system in certain orders of the 



1,413 ° f Bota ny 22:651-682. ph. 32, 33. 1908. 



in a 



