586 SUMMAKY OF CUBKENT RESEARCHES RELATING TO 



Intercellular Spaces between the Epidermal Cells of Petals.* 

 — While the cells of the epidermis of leaves fit close to one another 

 without any intervening spaces except the stomata, the case appears 

 to be very different, according to G. H. Hiller, with the epidermis of 

 petals, wlaere there are very often spaces between the cells, especially 

 in Dicotyledons. The size and form of these spaces vary with the 

 species ; in Linum usitatissimum they have a breadth of from 2 ' 63 to 

 7'175/x, and a length of from 13 '15 to 15-78 /a. The largest 

 measured had a diameter of 18 fj.. They are situated either between 

 the walls of the cells themselves, and then usually at the point of 

 contact of several cells, or in rib-like foldings of the cell-walls. On 

 the inner side of the leaf they are usually open, where not acci- 

 dentally covered by a parenchyma- cell, while on the outer side they 

 are always covered by the cuticle. They almost always originate 

 from ribs which must be regarded as foldings of the cell-wall, which 

 ribs split at a certain stage of development. Very rarely they occur 

 in epidermis with straight- walled cells, and then always from their 

 effort to round themselves off. They are then always found at the 

 point of contact of several cells. Intercellular spaces of this kind 

 may be observed in the petals of Musa rosacea and Erythrina crista- 

 galli. 



Contents of Sieve-tubes.t — E. Zacharias has examined, by ordi- 

 nary macrochemical tests, the contents of the sieve-tubes of Cuciirbita 

 Pepo, which flow out in large quantities when the stem is wounded, 

 and can be readily separated from the cell-sap. They consist of 

 albuminoids, non-albuminous organic substances, and inorganic salts. 



The albuminoid substances readily separate from the juice which 

 flows from the sieve-tubes, after standing for a short time, in the form 

 of a transparent, colourless, moderately stiff jelly. Chemical tests 

 show that this substance is of the nature of fibrine, mixed with a small 

 quantity of a substance insoluble in the gastric juice and in dilute 

 potash ley. When this substance has been removed by concentrated 

 alcohol, the filtrate turns the plane of polarization to the right. The 

 substance which remains is of the nature of dextrin, which is trans- 

 formed into glucose by dilute sulphuric acid. The presence of a 

 nitrate or nitrite can also be determined both in the aqueous solution 

 of the substance and in its ash. The question of the presence or 

 absence of amido-acids and of organic nitrogenous compounds soluble 

 in water in the contents of the sieve-tubes was not satisfactorily 

 settled. 



Of inorganic salts there was found in the ash distinct evidence of 

 the presence of magnesia. The probable presence in the sieve-tubes 

 of potassium phosphate was also indicated, and to this is probably due 

 the alkaline reaction of the juice. 



Organs of Secretion in the Hyperieacege.J — J. R. Green describes 

 the organs that secrete the ethereal oil or resin with which the 



* Ber. Deutsch. Bot. Gesell, ii. (1884) pp. 21-3. 



t Bot. Ztg., xlii. (1884) pp. 65-73. 



X Jom-n. Linn. Soc. Lond.— Bot., xx. (1884) pp. 451-64 (2 pis.). 



