20 Varietäten etc. — Physiologie. 



from a peripheral cotyledonary zone at the top of a more or less 

 massive proembryo. This reduces cotyledony in general to a com- 

 mon basis in origin, the number of cotyledons being a secondary 

 feature. The constancy in the number of cotyledons in a great group 

 is no more to be wondered at than a similar constanc}'- in the num- 

 ber of petals developed by the petaliferous zone. 



The authors believe that massive proembryos, as occur in Aga- 

 panthus represent the primitive condition of proembryos in Angio- 

 sperms, and that only from such a proembryo could the monocoty- 

 ledonous and dicotyledonous conditions have differentiated. After 

 this differentiation. the difference has become relatively fixed b}^ 

 the reduction of proembryos to filaments. While massive proembryos 

 occur in all the three great divisions of Angiosperms, they are no- 

 tably present among the Ranales, from which the monocotyledonous 

 branch seems to have arisen; and they are also retained by many 

 of the Monocotyledons, notably the Arales and Lüiales, and in 

 these groups one may expect to find occasional dicotyledony or 

 even polycotyledony. Jongmans. 



Bottomley, W. B., Some Accessory Factors in Plant 

 Growth and Nutrition. (Proc. Roy. Soc. B. LXXXVIII. p. 

 237—247. 1914.) 



The author reviews recent work on the subject of the presence 

 of accessory factors in normal dietaries of man and animals. These 

 substances are obtainable as phosphotungstic precipitates, and pos- 

 sibly belong to a new group of Nitrogenous Compounds. They 

 chiefly occur in plants and the investigation was to ascertain what 

 part if any they play in the metabolism of the plant itself. 



By treating peat vvrith certain aerobic soil organisms it had been 

 found that the bacterised peat contained in addition to the ordinary 

 plant food constituents, a substance which stimulated growth in a 

 remarkable manner and was possibly of the nature of an accessory 

 food body. This substance proved to be soluble in water and alcohol 

 and experiments shewed that it was absent from raw peat and 

 present in bacterised peat as a result of the treatment. As the latter 

 consists essentially in the production of soluble humates by bacte- 

 rial action, tests were made to ascertain whether the chemical 

 production of soluble humates would be equally efifective. This was 

 found not to be the case. The active substance is precipitated by 

 phosphotungstic acid, and this fraction proved to be quite as effec- 

 tive as the original alcoholic extract of the peat. In order to deter- 

 mine how far the growth stimulant in bacterised peat resembled 

 the "vitamines'' of Fürst, a further fractionation with silver was 

 carried out. The dry substance obtained was added to the nutrient 

 Solution in which plants were grown and enabled them to utilise 

 the food elements to a degree far in excess of those growing in a 

 pure food Solution. 



Fürst had demonstrated facts which indicated the possibility of 

 the development during germination of special growth substances 

 which enable the young erabryos to utilise the food materials present 

 in the seed. This may therefore be inhibited by the removal of the 

 seed , as soon as possible after germination, and this would render 

 the addition of such substances to the food Solution much more 

 marked. Wheat seedlings were treated thus and grown in pure food 

 Solution and in this plus the silver fraction of bacterised peat. After 



