538 SUMMARY OF CdRRENT RESEARCHES RELATING TO 



BOTANY. 



A. GENERAL, including- the Anatomy and Physiology 



of the Phanerog-amia. 



a. Anatomy.* 



Q3 Cell-structure and Protoplasm. 



Growth of the Cell-wall. t — Herr E. Strasburger continues his in- 

 vestigations on the growth and structure of the cell-wall, especially in 

 relation to Wiesner's discovery | of the constant presence of albuminous 

 substances in the cell-wall. Many phenomena connected with the growth 

 of the cell-wall hitherto inexplicable he now explains on the theory of 

 the entrance into it of the living protoplasm, the cytoplasm or hyaloplasm 

 of the cell. In the same way cutinized, suberized, and lignified cell- 

 walls owe their characters to the entrance of foreign substances from 

 without. 



The development was especially examined of the spores of the 

 Hydropteridese (Ehizocarpege). In Azolla the massulge are first formed 

 when the formation of the membrane of the microspores is completed. 

 Eound the microspores are formed clear borders, consisting of a fluid 

 derived from the surrounding protoplasm ; these borders unite with one 

 another so that finally a number of hyaline vesicles are contained within 

 the microsporange, separated from and surrounded by the hyaloplasm. 

 From these vesicles the massulse are formed, which are therefore derived 

 from the hyaloplasm which has entered the vesicles. When mature the 

 massulae resemble in structure cutinized cell-walls. The same substance 

 from which massulse and glochids are formed in the microsporanges gives 

 rise in the megasporanges to the peculiar floating apparatus. The 

 perinium on the megaspore of Salvinia is a structure of the same origin. 



In the formation of the pollen-grains of the Onagrariese a similar 

 process takes place ; and in those pollen-grains which are provided with 

 spines or other prominences projecting outwards, these are formed out 

 of a living substance which enters the extine from the hyaloplasm. 

 Similar observations were made on the development of the elaters of 

 Equisetum, on the spore-membranes of Biccia and Sjaliserocar^iis, on the 

 oogones of Peronospora, &c. 



In epidermal cells it was proved in a number of instances that the 

 cuticle-layer originates as a lamella of cellulose, and that it is only later 

 that the substance which brings about the cuticularizing enters the 

 cell-wall ; this substance is not cutin, but is a living constituent of the 

 body of the cell. In the processes of suberization and lignification the 

 nature of the changes is not so clear ; but all striation and stratification 

 are probably the result of the introduction into the constitution of the 

 cell-wall of a foreign substance derived from the hyaloplasm. 



Structure of the Cell-wall.§ — According to M. L. Mangin, the first 

 division-wall formed in cell-division consists of pectose, on both sides 

 of which layers of cellulose are then formed, while it increases itself in 



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

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

 Organs. 



t 'Ueb. d. Wachstlaum vegetab. Zellliaute,' 8vo, Jena, 1889, 186 pp. and 4 pis. 

 See I3ot. Centralbl., xxxvii. (1889) p. 394. 



% Cf. this Journal, 1886, p. 818. § Comptes Eendus, evil. (1888) pp. 144-6. 



