ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 85 



(4) Chemical Changes (including Respiration and Fermentation). 



Exhalation of Oxygen by fleshy-leaved Plants in absence of 

 Carbonic Anhydride.* — Herr A. Mayer, by former researches, has shown 

 that under certain conditions oxygen is exhaled by the leaves of some 

 plants in absence of carbonic anhydride. This is more especially the 

 case with the Crassulaceae ; and it was found that leaves of Bryophyllum 

 calycinum, which contain malates, after a period of darkness (during 

 night) have an acid reaction, but during the daytime this reaction 

 becomes much less. The author's experiments, made since 1883, show 

 that " acid leaves," during insolation in an atmosphere free from 

 carbonic anhydride, yield more oxygen the richer they are in free acid. 

 The acid present is malic acid ; and this acid and the calcium salt 

 diminish during insolation, just as if the whole consisted of free acid, 

 the products resulting from the change being starch, sugar, &c, and the 

 amount of oxygen which should be separated by the produced carbo- 

 hydrates agrees well with the quantity of oxygen found to be set free by 

 insolation. 



Respiration of the Potato.f — Herr J. Boehm gives the results of a 

 large number of experiments on the exhalation of carbonic acid by 

 potatoes, whether ordinary or sweet, injured or uninjured. As in the 

 case of seedlings of Phaseolus multiflorus, the intensity of the respiration is, 

 in most cases, independent of the partial pressure of oxygen, though 

 there are conditions under which this is not the case. Herr Boehm finds 

 that when cut into pieces, potatoes respire much more energetically than 

 when uninjured. The internal respiration is independent of external 

 injury, and is much more intense with sweet than with ordinary potatoes ; 

 but in both cases the internal respiration is greatly increased, with cut 

 potatoes, when they are previously placed for a day in moist air at a 

 temperature favourable for normal respiration. 



Action of Formose on Cells destitute of Starch. — By experiments 

 on Fraxinus Omus, Rubia tinctorum, Syringa vulgaris, and Caealia 

 suaveolens, Dr. C. Wehmer % has determined that formose (C 6 H 12 6 , 

 obtained by the condensation of formic aldehyde) belongs to the class of 

 carbohydrates which living leaves have not the power of converting into 

 starch ; agreeing in this respect with milk-sugar, ramnose, inosite, 

 dextrin, erythrite, trioxymethylen, and some organic acids ; and differing 

 from dextrose, levulose, galactose, maltose, cane-sugar, mannite, dulcite, 

 and glycerin. 



Commenting on this paper, Herr 0. Loew § disputes the accuracy of 

 some of Dr. Wehmer's results, and especially dissents from a conclusion 

 drawn by that gentleman from the fact that he was unable to obtain 

 starch from formose. This induces Wehmer to oppose the recent view 

 that formic aldehyde is the first product of assimilation in plants, but, 

 as Loew thinks, on insufficient grounds. 



7- General. 



Biology of Orobanche.|| — Herr L. Koch describes in detail the life- 

 history of several species of Orobanche. The seeds, which are produced 



* Landw. Versuchs-Stat., xxxiv. pp. 127-43. See Journ. Ckem. Soc, 1SS7, 

 Abstr., p. 988. t Bot. Ztg., xlv. (1887) pp. 671-5, 681-92. 



J Bot. Ztg., xlv. (1887) pp. 713-7. § Ibid., pp. 813-4. 



|| Koch, L., ' Die Entwicklungsgescbichte der Orobancheen,' 3S9 pp. and 17 pis , 

 Heidelberg, 1887. See Bot. Ceutralbl., xxxi. (18S7) p. 361. 



