624 SUMMARY OF CURRENT RESEARCHES RELATING TO 



nitrogen in Cystococcus humicola, and concludes that the alga does not 

 use the nitrogen of the atmosphere. It readily assimilates nitrates both 

 in light and darkness, and probably acts by reducing them in part to an 

 ammoniacal condition. It makes use with equal facility of ammoniacal 

 nitrogen probably by means of a partial oxidation ; light is not an 

 indispensable condition. It can use the nitrogen present in organic 

 compounds, such, for instance, as asparagin and peptone. 



Nutrition of Plants deprived of their Cotyledons.* — G. Andre 

 obtains the following results by depriving seedlings (of Haricot d'Es- 

 pagne) of their cotyledons at a very early stage. The removal is 

 followed by a complete check to vegetation ; no increase in dry weight 

 was observed in the two days following the operation. In the fortnight 

 following the removal the dry weight of 100 plants increased by 51 • 5 g. 

 of which 8 * 6 g. represented mineral matter. In the same period control 

 plants with cotyledons showed increases of 129 g. and 19 g. respectively. 



The author finds a remarkable parallelism between the relative 

 absorption of nitrogen and of phosphoric acid in the two sets of 

 seedlings. 



In a later communication f the author describes the variation in the 

 amount of potash and organic matters in a similar series of experiments. 



Klebs, G. — Willkiirliche Entwickelungsanderungen bei Pflanzen. EinBeitrag zur 

 Physiologie der Entwickelung. (Arbitrary changes in plant development. A 

 contribution to tbe physiology of development.) 



8vo, iv. and 16G pp., Jena (Fischer) 1903. 



Irritability. 



Resistance of Seeds to High Temperatures.! — H. H. Dixon describes 

 the results of experiments on the maximum temperatures seeds can with- 

 stand without losing their germinative power. The seeds were dried 

 and then exposed for at least one hour to the higher temperature. 

 Afterwards they were sown on moist sand. The highest temperatures 

 recorded, after exposure to which germination was possible, were 121° C. 

 with Medicago saliva, 120° with Convolvulus tricolor, 118° with Avena 

 saliva and Hordeum distichum. The time needed for germination is in- 

 creased by exposure to temperatures near the maximum. Long exposure 

 to a comparatively low temperature may prove more fatal than a short 

 exposure to a high temperature. 



Filippi, Domenic o. — L'azione degli anestetici sulla transpirazione dei vegetali. 

 (Action of anaesthetics on transpiration.) 



Atti d. Soc. Tosc. Set. Nat. (Pisa) Memor., XIX. (1903) pp. 91-105 (2 pis.)- 



Chemical Changes. 



Nature of Protoplasm and Enzymes. § — Th. Bokorny records the 

 results of his research on the action of various reagents on living cells. 

 He noted the action of alcohol of different percentages on yeasts and 



* Comptes Eendus, exxxvi. (1903) pp. 1401-4. 



t Tom. cit., pp. 1571-3. J Kep. Brit. Assoc, 1902, p. 805. 



§ Pfliig. Arch.,xc. Heft. 11 and 12. See also Centralbl. Bakt.,x. (1903) pp 252-61. 



