26 CONTINUITY OF PROTOPLASM.—PRIMORDIAL UTRICLE. 
these movements existed for the purpose of bringing every part 
of the living matter into constant communication with the 
nutriment-bearing sac. 
In most cases the presence of protoplasm may be readily 
detected by the use of reagents. Alcohol and weak acids cause 
it to shrink from the cell-wall (jigs. 87 and 42); a solution of 
iodine colours it brown, while sugar and sulphuric acid make 
it assume a pink colour. Protoplasm is extremely rich in 
albuminoids, which chemically con- 
sist chiefly of carbon, hydrogen, 
oxygen, nitrogen, sulphur, and phos- 
phorus, the most distinctive element 
being that of nitrogen. The gluten 
of Wheat is a good example of an 
albuminoid, and may be easily ob- 
tained by washing ordinary flour in 
a coarse muslin bag till all the starch 
has been got rid of, It then appears 
as a pale, grey, sticky substance, 
Fig. 42. Cell of the leaf of Junger- and when burnt gives off an offen- 
mannia Taylori, showing the gjye odour like that of burnt meat. 
protoplasm contracted by alco - Pecunl lok tl joi 
ok gkttes Mobil. rotoplasm also frequently contains 
globules of oil, granules of starch, 
and other similar substances. 
It has been recently shown by Gardiner, Hillhouse, Russow, 
Bower, and others, that in many plants the protoplasm of one 
cell is in communication with that of the cells around it, by means 
of threads of protoplasm which pass through the cell walls ( fig. 
43); and in many other instances where the continuity has not 
yet been clearly demonstrated, threads are found to pass from 
the main mass of the cell protoplasm to adjacent parts of the 
adjoining walls (fig. 44, 1), and this may occur where there are no 
pits nor pores as well as where such thin or pervious spets exist. 
‘fo what extent the continuity of protoplasm may by-and-by be 
found to obtain, itis useless to speculate, as at present it has only 
been proved in some parts of certain plants ; though these plants 
have widely different classificatory value, some being Phanero- 
gams (fig. 44, 1, 2, 3), while others are so low as the Alge (jigs. 
43 and 44, 4). 
The Primordial Utricle (fig. 39, p), as has already been ob- 
served, isthe thin layer of protoplasm which lines the cell-wall 
and forms the boundary of the central cavity filled with cell-sap. 
It is frequently so thin and transparent that it cannot be detected 
without the aid of reagents, which either colour it or cause it 
to separate from the cell-wall as mentioned above (fig. 42). 
Whilst living the primordial utricle is always in organic connex- 
ion with the cell-wall, which latter indeed is only matter that 
has been manufactured by the protoplasm, and then deposited 
upon its outer surface. By some authors the primordial utricle 
Se SS es oe 
