34 SCIENCE PROGRESS 



grown on to maturity. Those developed from embryos with- 

 out endosperms tend to be shorter with fewer and stouter 

 internodes, whilst their general development is retarded. 



Taxonomy. — In the Journal of Botany (January. — March) G. A. Boulenger 

 describes a new species of Rosa from Dorset, W. J. Hodgetts a new Desmid, 

 Roy a anglia, and J. A. Wheldon a new Lichen, Bilimbia cambrica, from 

 Snowdon. 



In the same Journal Colonel Godfrey figures and describes the essential 

 floral distinctions between Epipaciis violacea, E. latifolia and E. viridiflora v. 

 leptochila. 



Additional species are described belonging to the following genera : 

 Aspilia, Crassocephalum, Metalasia, Stocbe, and Vernonia (Compositae), 

 Hygrophila, Jtisticia, Rhinacanthus (Acanthaceae), Fai</'e/ia (Borraginaceae), 

 Solanum (Solanaceae), Phyllanthus (Euphorbiaceas), Crotalaria (Legumi- 

 noseae), and Dewevrella (Apocynacese). 



Economic. — Read and Smith [Ins. Sci. and Industry, Aus- 

 tralia Bull. 14) have investigated the properties of the fibre of 

 Posidonia australis. The fibres have a low tensile strength 

 and flexibility, but their commercial value can be greatly in- 

 creased by treatment with cold, dilute, mineral acids. The 

 ultimate fibres are about i mm. in length and consist of ligno- 

 cellulose. They exhibit great resistance to dilute alkalis, but are 

 readily affected by the halogens and exhibit a great affinity 

 for dyes. Apart from the high value as an insulating medium, 

 their use is advocated for coarse fabrics where resistance to 

 strain is not important but where resistance to chemical and 

 bacterial action is a necessity. 



PLANT PHYSIOLOGT. By Cyril West, D.Sc. (Lond.). A.R.C.Sc, 

 Botany School, Cambridge (Plant Physiology Committee). 



Dormancy, or Delayed Germination of Seeds. — Although the sub- 

 ject of dormancy, or delayed germination of seeds, is of great 

 importance from the economic point of view, and consequently 

 has attracted the attention of many workers in the past, it is 

 only of recent years that much attention has been directed to 

 its physiological aspect. Crocker (" Mechanics of Dormancy in 

 Seeds," Amer. Journ. of Bat., iii, 191 6, p. 99) has given an 

 excellent summary of our knowledge of the physiology of dor- 

 mancy in seeds up to, and including, the year 191 5, and has 

 pointed out that, broadly speaking, dormancy, or delayed 

 germination of seeds, can be attributed to one or more of the 

 following causes : (i) incomplete development of the embryo ; 

 (2) impermeability of the testa to water : (3) mechanical re- 

 straint offered to the expansion of the embryo and other 

 seed-contents by the seed-coats ; (4) inhibition or retardation 

 of the passage of gases to or from the embryo by the testa, 

 resulting in an accumulation of carbon dioxide within the 



