558 Floristik, etc. — Angewandte Botanik. 



breitung. (Actes Ille Congr. int. Bot. II. p. 43—50. 2 ng. 16 pl. 

 col. 1 carte. 1912.) 

 Tout en conservant l'ordre t'ourni par la systematique, l'auteur 

 parvient ä fournir des indications sur la dispersion geographique 

 en appliquant, sur les etiquettes, des teintes conventionnelles. II 

 montre, par des exemples, la methode, imaginee par lui, suivie au 

 Musee royal de botanique de Dahlem (Berlin). 



Henri Micheels. 



E. J. R., The effect of Grass on Fruit trees. (Nature. N°. 

 2206. p. 486—487. 1912.) 



Experiments at the Woburn Experimental Fruit Farm show 

 that growing grass exercises a deleterious effect on fruit trees, par- 

 ticularly on apples, the effect of grassing the ground after the tree 

 is planted being to arrest all healthy growth and to absolutely stunt 

 the tree. Various hypotheses have been put forward to explain this, 

 but none are so far really satisfactory. It does not seem that the 

 influence of the grass on the food supply is the determining factor, 

 nor does it appear that the growth of grass causes any sufficient 

 physical alteration in the soil to account for the results. If the 

 results of these experiments are confirmed it seems difhcult to avoid 

 the conclusion that the grass roots have actually excreted a toxin, 

 though, if it exists, it is extremely transient and disappears rapidly 

 frorn the soil. W. E. Brenchly. 



Pethybridge, G. H., The methods employed in testing 

 grass seeds. (Journ. Econ. Biol. VII. 2. p. 41—49. 1912.) 



The methods involved in determining the percentage of purity 

 of grass seeds as practised by the best known Continental seed 

 testing stations is contrasted with that employed at the Irish seed 

 testing Station. At the latter Station only the real impurities such 

 as weed seeds, dirt, etc. are removed during the purity test; whe- 

 reas, in the case of the larger grass seeds, in addition to removing 

 the real impurities, the empty, or supposedly empty, seeds are 

 removed at the better known Continental stations. This procedure 

 also influences the percentage of germination, for at Continental 

 stations this test is carried out on selected seeds, and higher per- 

 centages of germination (but lower of purity) are therefore obtained. 

 The chief reasons why the non-selective method was adopted at the 

 Irish Station are 1) With the best-grass seeds it gives results which 

 fully characterise such seeds, 2) Farmers as a rule lay more stress 

 on the germination of seeds than on their purity and the Irish 

 method indicates more clearly second and third rate qualities of 

 seeds in respect of germination. 3) There is considerable difficulty, 

 in accurately determining what seeds are empty, and the perso- 

 nality of the tester comes into play. In the Irish method this diffi- 

 culty is eliminated. 4) Concordant results within the limits of 

 reasonable latitude are obtainable where successive tests of the same 

 or duplicate samples are made. Examples showing the correctness 

 of these views are given in the paper. Author's abstract. 



Ranninger. Ueber das Entbluten der Kartoffeln. (Wiener 

 landw. Zeit. LXI. 74. p. 832. 1911.) 

 Eine Parzelle von 2a wurde stark gedüngt und die Kartoffeln 



