204 Alfr(^d J. Eiuart : 



trates were then applied to both the salts. All the tests were posi- 

 tive, thus confirming that these were salts of tartaric acid. 



The importance of this method of producing sugar lies in the 

 fact that it iS a rapid and well dehned action, yielding definite 

 salts, namely, sodium and calcium tartrates, and that the 

 amount of sugar produced, particularly of hexose sugars, is large, 

 being intermediate between the weights of the calcium and sodium 

 salts. It is not, however, likely that this mode of producing sugar 

 from formaldehyde is of any importance in the living plant, since 

 it involves a high temperature, and the presence of an abundance 

 of two free alkalies. 



WiUstaUer's and StolUs^ work on Photo-synthesiis. 



These authors found that all attempts to produce extracellular 

 photo-synthesis failed, which they conclude is owing to the absence 

 of a hypothetical enzyme from extracted chlorophyll. They found, 

 however, that slight pressure applied to the leaf completely stopped 

 photo-synthesis, which rather supports my own view than an 

 orderly physical arrongement of the chlorophyll molecules in the 

 chloroplastid is an essential factor in continuous photo-synthesis, 

 and that a disturbance or disorganization of this arrangement may 

 be partly responsible for the temporary inactivity into which an 

 apparently normal chloroplastid may be thrown by various agencies 

 or treatments, which wlien extreme, lead to death and permanent 

 disorganization. 



They also conducted experiments on living leaves by passing a 

 mixture of air and carbon dioxide over them in vessels on a water 

 bath exposed to light, and estimating the amounts of carbon 

 dioxide assimilated. They found that the assimilation was not 

 always proportional to the chlorophyll content, a fact already well 

 known to the plant physiologist. 



In leaves lich in chlorophyll the authors found that increased 

 illumination did not increase the assimilation, whereas a rise of 

 temperature did, while in leaves deficient in chlorophyll a rise of 

 temperature had little effect, and increased illumination rendered 

 the assimilation of carbon dioxide more active. Hence they con- 

 clude that their hypothetical enzyme is in relative excess, and only 

 exercises its maximum effect when the chlorophyll is working at full 

 pressure. 



1 Berichte, 1915, 48, 1540. 



