616 SUMMARY OF CURRENT RESEARCHES RELATING TO 



especially of the phosphoric acid, potassa, and magnesia ; the proportion of 

 dissolved mineral substance is inverse to the advance of growth. 



The author regards the transformation of starch into sugar as a purely- 

 chemical change, independent of any micro-organisms, for it is brought 

 about by diastase even in the presence of the most powerful antiseptics. 

 Seeds can therefore germinate without the assistance of these organisms. 

 Ammonium salts are, he states, formed in germination. 



Experiments were tried on the formation of solanine and solanidine in 

 the potato, to determine whether they are produced in germination. He 

 finds that they are not reserve-substances, but a diffusible form of nitrogen 

 compounds. Amygdalin is also a plastic substance, and not a simple pro- 

 duct of metastasis. It disappears only slowly on germination. 



According to the author's observations, starch-grains may resist the 

 unassisted action of diastase for months. In the rapid formation and trans- 

 formation of the carbohydrates during germination he believes the albumi- 

 noids to play an important part, and that they are derivatives of a simpler 

 substance, formic aldehyde. 



Calcium is found universally in the cell-wall, and is probably essential 

 to the formation of cellulose. The fatty acids are formed at the expense of 

 the albuminoids, independently of glycerin ; on germination, fatty oils are 

 Bplit up into glycerin and a fatty acid. Sugar is not the invariable form 

 assumed by carbohydrates during transport ; it is not present in seedling 

 hemp, nor in the epithelium of the scutellum of grasses. 



Germination of the Date-palm.* — Although the date-palm comes under 

 the denomination of " desert plants," Herr G. Firtsch finds the structure of 

 young seedlings to present all the features of plants growing in wet situa- 

 tions, and requiring a large amount of moisture for their sustenance, such 

 as the absence of root-hairs. The development of the seedling, and the 

 structure of its various parts, are described in detail. 



(2) Nutrition and Grrowth. 



Apical Growth of Leaves.f — Herr P. Sontag has investigated the 

 duration of the apical growth in leaves belonging to various divisions of the 

 vegetable kingdom. In Nephrolepis and the Gleicheniacese the apical growth 

 is unlimited, while in most FilicinsB it ceases after the formation of the 

 lateral lobes. The same is the case in some Cycadea3. In the leaves of 

 Coniferse apical growth ceases early, while intercalary growth may con- 

 tinue for several years. In Monocotyledons apical is very inconsiderable 

 compared to intercalary growth. 



In the leaves of Dicotyledons there are three types, viz.: — (1) Inter- 

 calary ; apical growth ceases soon, when the leaf has attained a length of 

 from • 5-2 mm., the lateral portions being formed from a point below the 

 apex. (2) Apical ; all the lateral portions are formed in acropetal succes- 

 sion from the apex ; this mode is specially characteristic of UmbelliferEe. 

 (3) Mixed, some of the lateral parts being formed from the apex, others 

 from an intercalary growing point ; this is the case in all Compositse. 



Chlorophyllous Assimilation.| — Prof. T. W. Engelmann replies to the 

 objection against his statement that the maximum absorption of carbon 

 dioxide by green leaves takes place in the red of the spectrum, founded on 



* SB. K. Akad. Wiss. Wien, xciii. (1886) pp. 342-54 (1 pi.). 



t Sontag, P., ' Ueb. Dauer d. Scheitelwachsthums u. Entwickelungsgesch. des 

 Blattes,' 31 pp., Berlin, 1886. See Bot. Centralbl., xxx. (1887) p. 9. 

 I Bull. Soc. Belg. Micr., xiii. (1887) pp. 327-33. 



