296 Gelehrte Gesellschaften. 



employed. The repulsion of such forms is here the only safe test for 

 an evolution of oxygen. 



There is no ä priori reason, why the chloroplastids, in a cell 

 the cytoplasm of which had been killed, might not, especiully, 

 bearing in mind the now definitely proved fact, that isolated 

 chloroplastids raay continue for a short time to assimilate, also 

 for a time continue, if exposed to light, to evolve oxygen In 

 deed, at one time, it seemed as if certain observations, that 

 Pringsheim and myself had made, pointed to this conclusion. 

 The completed investigation shewed, however, (see p. 415. A^. 

 p. 145. A^) that whilst an evolution of oxygen might continue in 

 certain cases to take place from a chlorophyllous cell for a short 

 tirae after its death had occurred, such evolution was, so far as 

 my own observations went, independent of light and, therefore, not 

 a product of a process of COa-assimilation. The cases given by 

 Kny may possibly be examples of the continuance of CO2- 

 assimilation by the chloroplastids, for a short time after the death 

 of the cytophism. As shewn above, there is no ä priori reason 

 why such should not take place. No results however obtained 

 by means of the Bacterium method can be considered as satis- 

 factory unless pure cultures are worked with, adequately closed 

 cell preparations are employed, and füll attention is paid to the 

 Various special precautions which the researches of Engel mann 

 and myself have shewn to be necessary. Otherwise the use of 

 the Bacterium method is more likely to retard than accelerate 

 scientific progress in this direction, naraely in elucidating problems 

 connected with COä-assimilation. 



References, 



A'. = On Assimilatory Inhibition in Plauts. Journal of the Linnean 



Society. Botany. Vol. XXXI. To 461. 1895. p. 364. 

 A.-. = Do. Vol. XXI. To 576. 1896. p. 554. 

 A*. = On the Evolution of Oxygen from Colom-ed Bacteria. Journal 



of the Linnean Society. Botany. Vol. XXXIII. To 155. 1897. 



p. 123. 

 A*. = The Effects of Tropical Insolation. Annals of Botany. Vol. XI, 



No. XLIII. To. 480. p. 439. Sep 1897. 

 B'. = Ou the Power of with stauding Dessication in Plauts. 



Transaction L'Pool. Biolos^ical Society. Vol. XI. To. 159. 1897. 



p. 151. 



23. October 1897. 



Gelehrte Gesellschaften. 



The Botanical Society of America. (Bulletin of the Torrey Botanical Club. 

 Vol. XXIV. 1897. No. 9. p. 449—450.) 



