^9o8] CURRENT LITERATURE 2S3 



Anatomy of Tmesipteris.— Miss Sykes^^ has investigated this interesting 

 genus from material sent by Mr. A. P. W. Thomas of New Zealand, comprising 

 the two species T. tanncnsis and T. lanccolata. The genus consists of ei)iphytic 

 species on tree ferns in Xew Zealand, Australia, and Polynesia. Only adult 

 plants have ever been obtained, and the gametophyte is entirely unknown. Natu- 

 rally the investigation by Miss Sykes has to do chiefly with the anatomy, and an 

 outhne of her results is as follows, in part confirmatory of previous work. 



In the rhizome there occurs a protostele, which has usually two exarch pro- 

 toxylem groups, but in passing to the aerial branch, pith arises in the center of the 

 stek and quickly expands to form a large tissue. This is a case of a protostele 

 passmg directly into an ectophloic siphonostele, without the intermediate stage 

 of an amphiphloic siphonostele; and all this occurs at a level at which no leaves 

 have yet arisen. It was discovered that the course of the vascular bundles as 

 described by Bertrand for a sterile branch is exactly similar to that found in a 

 fertile branch; that is, the single bundle entering the axis branches into three, the 

 two lateral traces supplying the leaves, and the central one representing the vascu- 

 lar supply of the apex. In the fertile branches the central bundle supplies the 

 s>Tiangium, and indicates to the author that the so-called **sporophyte" is cauline 

 in nature, consisting of an axis bearing two leaves, and at its apex a synangium 



sporogenous 



Attention 



sporo 



is called also to the essential similarity in the formation of leaf and branch traces, 

 It bemg claimed that the presence of a gap depends simply on the greater length 

 of time elapsing between the division of a xylem group to form a trace and the 

 departure of that trace from the stele. In fact, if the so-called ' 

 really a sporophyll, the exit of its trace results in a leaf -gap; but according to Miss 

 Sy-kes this is a branch-gap. The conclusion as to relationship, apparently inevi- 

 table in all such pieces of work, is that the Psilotaceae had better be retained as a 

 separate division of Pteridophytes, the Psilotales.— J. M. C. 



Role of certain elements-— The precise physiological role which the essential 

 chemical elements play in plant life has long been an attractive subject for investi- 

 gation. With advancing chemical knowledge the methods of experimentation 

 have been greatly improved. It must be said that the older experiments have 

 little value, and it is doubtful whether even the newest have verj' much, because 

 the chemistr}^ of the proteids is still such an enigma. Reed has undertaken the 

 study of the effects of four elements, potassium, phosphorus, calcium, and magne- 

 sium, upon certain filamentous algae, protonemata of mosses, prothallia of ferns, 



Basidiobolus.'^ His techniqu 



used 



^5 Sykes, M 



G., The anatomy and morphology of Tmesipteris. Annals of 

 Botany 22:63-89. pis. 7, 8. figs, /j/1908. 



'^ Reed, H. S., The value of certain nutritive elements to the plant cell. Annals 

 of Botany 21 :5oi-543. figs. 2, 1907. 



