564 Biologie. — Morphologie etc. — Physiologie. 



(Urfeige), que celui-ci se rencontre dans la localite dite „la Fatuc- 

 chia" pres Florence, Longo ayant examine sur place le specimen 

 cite par Ravasini n'y a pas reconnu les caracteres que Tschirch 

 et Ravasini attribuent ä leur Urfeige. R. Pampanini. 



Sabachnikoff, V., Action de l'acide sulfureux sur le pollen. 

 (C. R. Soc. ßiol. Paris. LXXII. p. 191. 1912.) 



1° L'acide sulfureux, ä la concentration de 1 p. 48,000, agissant 

 pendant 48 heures, n'influence pas la faculte germinative du pollen. 

 2° Les concentrations au-dessous de 1 p. 13,000 detruisent presque 

 toujours la faculte germinative lorsque cette action s'exerce pendant 

 3 heures. 3° On peut admettre que la concentration de 1 p 13,000 

 est la concentration mortelle limite, lorsque Faction de l'acide, se 

 prolonge 24 heures. 4° Les pollens intoxiques et non tues peuvent 

 germer d'une facon anormale. H. Colin. 



Brenchley, W. E., The influence ofCopper Sulphate and 

 Manganese Sulphate on the growth of Barley. (Ann. 

 Bot. XXIV. p. 571-583. 1910.) 



Experiments on Barley were carried out by the method of 

 water-cultures, special precautions being made to eliminate errors 

 due to faulty manipulation. The plants were grown in specially 

 distilled water, either with or without the addition of nutrient 

 salts, and in the presence of various concentrations of Copper 

 Sulphate and Manganese Sulphate. At the close of the experiments 

 the plants were thoroughly dried, and the dry weights were recor- 

 ded, the results being plotted as curves. Owing to the individuality 

 of the plants the results of several investigations with similar con- 

 centrations were compared before any conclusions were drawn. The 

 ultimate conclusions were as follows: 



1. The action of plant poisons in dilute Solutions is masked by 

 the presence of nutrient salts, which thus enable plants when 

 grown in such Solutions as water-cultures to endure a much greater 

 concentration of the toxic substance than in the absence of nutrients. 



2. Copper Sulphate, which is a definite poison to Barley, does 

 not have any stimulative effect in very dilute Solutions, even at so 

 low a concentration as 1 : 10,000,000 C. S. 



3. Manganese Sulphate, though not an actual toxic to Barley 

 retards the growth very considerably if supplied in moderate quan- 

 tities. Minute traces of the salt have a decided stimulative action 

 both on the root and shoot. 



4. When supplied in sufficient concentration Manganese is taken 

 up by the plant and deposited in the lower leaves. 



W. E. Brenchle3 r . 



Dümmer, R., Grape sugaras an Excretion in Platyceriwn. 

 (Ann. Bot. XXV. p. 1205—1206. Oct. 1911.) 



Three species of Platycevium were found to possess internal 

 lacunae on the lower surface of the young barren fonds; from them 

 grape sugar was exuded. 



The sugary excretions may be an adjunct to mutualism between 

 the plant and ants. E. de Fraine. 



