402 SUMMABY OF CURKENT RESEARCHES RELATING TO 



BOTANY. 



A. GENERAL, including- the Anatomy and Physiology 



of the Phanerogamia. 



a. Anatomy.* 



Q) Cell-structure and Protoplasm. 



Rotation of Protoplasm.t — Herr J. B. Schnetzler finds the elongated 

 cell in the protoneme resulting from the germination of the oosperm of 

 Chara fragilis to be a very favourable object for observing the phenomena 

 connected with the rotation of protoplasm. He believes it to be 

 essentially a function of respiration, that is, of the chemical changes 

 produced by the osygen of the atmosphere ; and compares it to the 

 property of the pollen-grain to emit pollen-tubes, which is equally 

 dependent on the free access of air. If the germinating Chara is 

 immersed in irrespirable gases, such as hydrogen, nitrogen, &c., or in 

 pure olive-oil, the movement of the protoplasm rapidly ceases, and the 

 balls of dense protoplasm which float on the surface of the more fluid 

 protoplasm assume a granular appearance, and surround themselves 

 with a delicate pellicle. 



Growth of Albuminous Composition of Cell-walls. :j: — Dr. I'. G. 

 Kohl has examined the structure of the hairs on many species of 

 Borraginese, Moracese, Urticacese, and Cucurbitacese, which exhibit a 

 very marked thickening at their apex, followed by a partial calcification 

 or silicification. This thickening is efi'ected neither by apposition nor 

 by intussusception, but by the deposition of fresh masses of cellulose 

 in a manner similar to that described by Krabbe § in the bast-fibres of 

 Apocynaceae and Asclepiadeee. These masses of cellulose are in the 

 form of caps placed one within another, and between them are masses of 

 protoplasm. This structure is exceedingly well seen in the hairs of 

 Symphytum officinale, after the calcium carbonate has been first removed 

 by dilute hydrochloric acid. The multicellular hairs of the Cucur- 

 bitacesB show in addition local thickening of the cell-wall by true 

 apposition. The reaction with Millon's reagent, even after first treating 

 with hydrochloric acid, as proposed by Wiesner,|| failed to detect the 

 least trace of albuminous substance in the cellulose-caps themselves. 



Contents of the Cell.^ — Herr J. H. Wakker states that according to 

 the present state of our knowledge, the cell-protoplasm consists of: 

 (1) the parietal layer or hyaline protoplasm, which chiefly serves merely 

 as a protective organ for the rest, and for this purpose forms also the 

 cell-wall ; (2) the granular or streaming protoplasm which is concerned 

 with the transport of nutrient material ; (3) the nucleus, the function 

 of which has not been determined experimentally ; (4) the amyloplasts, 

 to which belong the chlorophyll-grains; and (5) the tonoplast, from 

 which the turgidity of the cell is derived, but which has also other 



* This subdivision contains (1) Cell -structure and Protoplasm; (2) Other Cell- 

 contents (including Secretions); (3) Structure of Tissues; and (4) Structure of 

 Organs. 



t Arch. Sci. Phys. et Nat., x.^i. (1889) pp. 100-7. 



% Bot. Centralbl., sxxvii. (1889) pp. 1-6 (1 pi.). 



§ Cf. this Journal, 1887, p. 272. H This Journal, 1886, p. 818. 



•n Jahrb. f. Wiss. Bot. (Pringsheim), xix. (1888) pp. 423-96 (4 pis.). 



