257 
ON CAUSES INFLUENCING THE DIRECTION OF 
GROWTH, AND THE ORIGIN OF MULTICEL- 
LULAR PLANTS. 
By Grorcz Masser. 
(Piate 277.) ’ 
In Alge the presence of a more or less gelatinous membrane 
exterior to the true cell-wall, and extending continuously over every 
part of the plant, is not uncommon. In the Floridea such a mem- 
the cell-wall; and further, that at first it closely resembles ae 
asm in many of its properties, both physical and chemical, 
becoming blackened with nitrate of silver prepared according to 
a similar effect. If treated with an aqueous solution of iodine in 
potassic iodide, it becomes yellow-brown ; and finally, if treated 
with nitric acid and afterwards with dilute potassic hydrate 
pataasic xanthoproteate is formed, which assumes a bright yellow 
colour, proving the presence of protein substances. The above 
tained in ca 
r 
Callithamnion, Ptilota, and Polysiphonia, are preferable to the green 
filamentous Algs, as in the latter the terminal cell is not neces- 
sarily the youngest, in fact rarely so after the formation of the first 
three or four cell wg ther increase of cells being due to interstitial 
growth _ divi 
The f regoing peedres coincide with Berthold’s theory,} 
that in spores, teas cellular Alge, and on free cell-surfaces generally, 
a film of pro toplaam extends over the cell-wall, the latter being 
considered ~ exercise a SU g rather than a protective function. 
alge it can be clearly demonstrated that the formation of the 
cellulose nial never precedes that of the mucilaginous sheath ; 
and it is also a fact well known to biologists that in very young 
lls it is impossible to demonstrate chemically the presence of 
* «Unters. Bot. Inst. Tubingen,’ ii, (1886). 
+ ‘Botanical Micro-Chemistry.’ American ed., p. 40. 
t ‘Studien tiber Proto toplasmamechanik,” Leipzig, 1886. See also Prof. H. 
Marshall Ward in ‘Natare, xxxy. (1887). 
Journat or Borany.—Vow. 25. ([Sxpr., 1887.] age 
