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SUMMARY OF CURRENT RESEARCHES RELATING TO 
BOTANY. 
A. GENERAL, including the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
(1) Cell-structure and Protoplasm. 
Callus and Paracallus.* — According to Mr. S. Le M. Moore, two 
substances have hitherto been confounded under the name of callus, — 
true callus, which neither gives proteid reactions nor peptonizes, and a 
proteid substance to which he gives the term paracallus. Both sub- 
stances have the function of obliterating the sieve-pores ; their micro- 
chemical reactions are given in detaihf 
Mr. Moore corrects his previous statement that the callus of the 
vegetable-marrow gives proteid reactions. On the abaxial side of the 
bast of the fig, the sieve-plates are closed by paracallus which results 
from the hardening of the “ Schleimkopf.” In Ballia we find para- 
callus alone ; Rosa canina , Ampelopsis hederacea and Veitchii , the fig, 
and Macrocystis pyrifera have paracallus as well as callus, while callus 
alone occurs in the ash and the elm. True callus resists the action of 
diastatic ferments, but dissolves in a solution of gum arabic ; hence 
there is probably a callolytic ferment in the gum, though the author 
has not been able at present to detect it. The function of both callus 
and paracallus is to protect the plant by preventing the formation of 
new shoots under only temporarily favourable conditions of heat, light, 
or moisture. 
Alleged Proteid-substances in Cell- walls.}: — Mr. S. Le M. Moore 
has investigated the alleged occurrence of proteids in cell-walls, and 
thinks the reactions may possibly be due rather to special conditions of 
tannin or to the presence of glucosides. That the substance found is 
not a peptonizable proteid is shown by the fact that the reactions are ex- 
hibited as well after peptonization as before; nor can it be a tyrosin, 
since the tests remain after soaking in hydrochloric acid. Catechu 
gives many of the reactions of proteids. The behaviour of lignified 
cell-walls to various reagents proves the existence in them of an iron- 
greening tannin ; this occurs in the meristem of the stem of Isoetes 
lacustris ; an iron-blueing tannin is found in the collenchyme of Rosa 
canina. The hard bast of the fig contains a glucoside in its walls. 
The evidence of the presence of a glucoside is often obscured in 
lignified cell-walls by the appearance in them of a red colour on boiling 
with dilute hydrochloric acid. If the cell- walls contained a proteid, 
they should take up carmine and anilin, which they do not. It is 
possible that the presence of a glucoside in lignified cell-walls may 
give them their property of conducting fluid. The precisely similar 
colour assumed with methyl-green by lignified cell-walls and by the 
* Journ. Linn. Soc. (Bot.), xxix. (1892) pp. 231-40 (1 pi.). Cf. this Journal, 
1891, p. 615. t Cf. infra, p. 711. 
X Journ. Linn. Soc. (Bot.), xxix. (1892) pp. 241-62. Cf. this Journal, 1888, 
p. 602. 
