ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 983 



difference in the chemical and physical properties of starch-substance and 

 amylodextrin ; and states that none of the dextrins resulting from the action 

 of ferments or acids on starch-substance are coloured by iodine. Erythro- 

 dextrins do not exist; even dextrins of high rotating power can be so 

 completely purified that they are no longer coloured by iodine. A dextrin 

 can be produced for which (a) D = 194*8, and which is nevertheless not 

 coloured by iodine. Where the red colouring is exhibited, it results from 

 an admixture of amylodextrin. 



Proteinaceous bodies in Epiphyllum.* — Herr. V. Chmielewsky has 

 reinvestigated the bodies found by Molisch in the parenchymatous and 

 epidermal cells of the branches of Epiphyllum (truncatwrn), and corrects his 

 description in one respect, stating that they are insoluble in alcohol. 

 From their chemical reaction he regards them as of the nature of globulin, 

 and believes them to be excretory rather than reserve-substances. He finds 

 them in quite as large quantities in old as in young branches, and also 

 that they are not used up when the plant is starved, 



Carrotene in Leaves.j — M. A. Arnaud states that carrotene is always 

 found in the leaves of plants in full vegetation. The amount is equal on 

 an average to about • 1 per cent, of the weight of the dried leaves, and it 

 must exert a considerable influence on their colour. 



Calcium oxalate in Aleurone-grains.| — According to HerrA.Tschirch, 

 the crystals of calcium oxalate found in aleurone grains of seeds are some- 

 times again completely dissolved when the seeds germinate, showing that 

 they must have a function as reserve food-materials. This is especially 

 well seen in the lupin. Herr Tschirch also describes the various crystalline 

 forms which the calcium oxalate assumes in the aleurone-grains of seeds. 



Nitrates and Nitrites in Plants.§ — Dr. H, Molisch states that nitrates 

 occur more abundantly in herbaceous than in woody plants, while in no 

 single instance has he been able to detect the presence of nitrites, which 

 are injurious to plants even in very dilute solutions, and are reduced by 

 them with extraordinary rapidity. Nitrates can, on the other hand, remain 

 weeks, or even months, within the cells of plants without being decomposed. 

 The nitrates found in plants are never the result of the oxidation of nitrites 

 or of ammonia salts in the cells, unless under the influence of bacteria, but 

 are always absorbed as such from the soil. 



Biological Import of Raphides.]] — Prof. E. Stahl calls attention to the 

 less obtrusive protective features exhibited by many plants. Numerous 

 points of external and internal structure are, he maintains, only fully 

 understood when considered in relation to the fauna which would destroy 

 the plants if not in some way protected. At present, however, he only notes 

 that the abundant raphides in plants are not wholly to be regarded as 

 useless excretions, but also as protections against snails and other destruc- 

 tive foes, which are at least thus restricted in their ravages. Snails have 

 been observed to confine their voracity to those parts of certain plants 

 where crystals were absent. Arum maculatum, usually regarded as 

 poisonous, owes its burning and repulsive taste solely to the presence of 

 very numerous raphides which penetrate the mucous membrane of the 

 mouths of those animals which attempt to devour it. 



* Bot. Centralbl, xxxi. (1887) pp. 117-9 (1 pi.). Cf. this Journal. 1886, p. 89. 

 t Comptes Kendus, civ. (1887) pp. 1293-6. Cf. this Journal, 1885, p. 670. 

 X SB. Gesell. Naturf. Freuude Berlin, April 19, 1887. See Bot. Centralbl., xxvi. 

 (1887) p. 223. 



§ SB. Akad. Wiss. Wien, May 5th, 1887. See Bot. Ztg., xlv. (1887) p. 454. 

 H Jenaische Zeitschr. f. Naturwiss., xx. (1887) pp. 145-7. 



