330 Physiologie der Zellen, Gewebe und Organe. 



sehen Forschungsergebnisse berücksichtigt sind, so daß es für manche Abschnitte 

 ein Spezialwerk der physiologischen Chemie zu ersetzen vermag. Es wird auch 

 diese IL Auflage bald einen Freundeskreis gefunden haben. Dohrn. 



*.)76) Brown, H. T., Some studies on Yeast, In: Annais of Botany, Bd. 28, 

 Heft 2, S. 197—226, 1914. 



The first part of the paper deals with the relation of cell-reproduction to 

 thesupply of free oxygen. The previous results of Slator and of Adrian Brown 

 are referred to, and the conclusion reached may be stated in the authors own 

 words: "During the period of active reproduetion yeast in a suitable medium in 

 which access of oxygen is limited to that initially present in Solution in the li- 

 quid, the number of cells present at any moment is directly proportional to the 

 time." The resulting curve is practically a straight line, and the rate of increase 

 an arithmetical rather than a geometrical one. The two most potent Controlling 

 factors are the amount of free Oxygen at the beginning, and the inhibiting ef- 

 fect of the increase in alcohol. C0 2 and the non-volatile produets of fermenta- 

 tion were shown by A. Brown to have no effect. The dissolved oxygen is ab- 

 sorbed at once, before cell-budding begins. Whatever the concentration, the ab- 

 sorption of oxygen by the yeast cell progresses as a linear funetion of the time. 

 just as the invertive, fermentative and reproduetive actions do. This is because 

 they all depend on the cell metabolism. 



The second part of the paper deals with heat formation during fermentation. 

 Pasteur believed that when the yeast was reproducing freely its fermenta- 

 tive power was in abeyance in aerobic conditions. It has since been shown that 

 when well supplied with oxygen, yeast shows as much or more fermentative 

 power than in anaerobic conditions. 



The natural habitat of the yeasts is the skins of fruits, and when the latter 

 are ruptured the yeasts are in a medium rieh in sugars and with a plentiful oxy- 

 gen supply. This is very different from the artificial conditions under which 

 yeasts are eultivated. In the natural condition the oxygen supply renders ex- 

 tremely rapid growth possible, and to allow this to continue an extra source of 

 energy is necessary. This is supplied by the auxillary process of fermentation, 

 and this fermentation was originally an aid to the all-important process of re- 

 produetion. Gates. 



977) Breiichley, TV. E., On the action of certain Compounds of zinc, arsenic, 

 and boron on the growth of plants. In: Annais of Botany, Bd. 28, S. 283 — 301, 

 1914. 



The writer points out that discordant results on the effects of poisons frequently 

 depend upon the medium in which the plants are eultivated, and the consequent amount 

 of adsorption. During to this fact a greater quantity of the poison is usually required 

 to exert a toxic effect in soil than in water eultures, and a strength of poison which is 

 toxic in water eultures may exert a stimulating effect in soil. 



Elaborate results of water eultures with peas, barley and other plants are given. 

 For example, part of B 2 3 in 25 million of water produced a stimulating effect on the 

 growth of pea seedlings. ZnS0 4 is found to be very toxic to barley and peas, and no 

 evidence of Stimulation was obtained even when the strenght was diluted to 1 : 200 000000. 

 Arsenious aeid and sodium arsenite were found to be more toxic than arsenic aeid and 

 the arsenate, but no Stimulation was obtained in any case. Boric aeid, being less poi- 

 sonous, gives Stimulation effects at the lower concentrations. Gates. 



978) Robinson, W., Some experiments on the effect of external Stimuli 

 on the sporidia of Puccinia malvacearum (Mont.). In: Annais of Botany, 

 Bd. 28, Heft 2, S. 331—340, 1914. 



The spores of the fungus were eultivated in a Van Tieghem cell, and its 

 reactions to various substances studied. The results of de Bary,Miyohsi, Massee 



