RECENT ADVANCES IN SCIENCE 573 



suggestive. In dealing with the zoid of the Phseophyceae, the 

 lateral position of the flagella is regarded as a derived one. 

 The anterior is supposed to be a survival of the plankton state, 

 which had for its function the vertical traction of the organism 

 towards the light. It has been retained, in still-water forms, 

 as a means of approximating the gametes, but the flagella tend 

 to diminish in size in algse of disturbed water. 



In " Plankton Phase and Plankton Rate," the same writer 

 brings together the data as to concentration of organisms, 

 which are suspended and autotrophic, in the surface of the sea. 

 Lohman, in Kiel Bay, estimated this to be from 500,000 to 

 2 1 millions per litre, though the Plymouth data are lower. 

 Dr. Church construes the inevitable supposition of autotrophic 

 organisms as the first form of life, as indicating the existence 

 of a " Plankton Epoch." Benthic organisms are compared 

 with plankton on the basis of their output of gametes. The 

 amount of plankton is possibly determined by the concentration 

 of P and N ions, all of which are approximately present in the 

 proportion of 1 in 10 million. 



Economic. — The application of Botanical Science to 

 economic problems has been vigorously prosecuted of recent 

 years, especially in the Colonies. Prof. Cockayne, in New 

 Zealand (N.Z. Journ. Agric), has been investigating the Montane 

 Tussock-Grassland, which is dominated by Festuca novce- 

 zealandioe, but comprises some 250 spp. of flowering plants, of 

 which 40 are introduced. Of this large number only a few are 

 eaten by the mountain sheep which are here pastured. The 

 prevalence of the inedible species is such that much of the area 

 only carries one sheep to five acres. The nutritious species are 

 kept in check through grazing by rabbits, and fires likewise favour 

 undesirable forms. Danthonia pilosa is the species most to be 

 encouraged, as also some introduced plants such as Trifolium 

 repens and Dactylis glomerata. Prof. Cockayne gives useful 

 data obtained experimentally on the relative palatability of 

 various species, which showed that sheep preferred Poa pra- 

 tensis, Dactylis glomerata, Hierochloe redolens, Danthonia semi- 

 annularis, Holcus lanatus, and Hypochceris radicata. This was in 

 a mixed pasture with numerous species, most of which (some 

 80 spp.) were untouched except by rabbits. 



M. Renouard {La Nature, Oct. 191 9) has dealt with the 

 textile fibres experimented upon by the Germans during the war 

 to replace the imported cotton and jute. Considerable hopes 

 were based on the Nettle, and several large companies, one 

 with a capital of over 15,000,000 marks, were floated for its 

 exploitation. The nettle, however, only yielded 8 to 12 

 per cent, of very fine fibre from 20 to 60 mm. in length, 

 or about 33 lb. per acre. The fibres of Broom, as in France, 



