438 Mr. A. Henfrey on the Progress of Physiological Botany : 
duces can only indicate a compound of iodine with starch. Iodine 
in a divided condition, whether dissolved or in powder, is always 
brown ; but that the blue compound which fibre-substance (cel- 
lulose), iodine and sulphuric acid produce, when washed away 
with water leaves a residuum which gives no blue colour unless 
sulphuric acid is again applied, implies that the starch which has 
been found has been converted into dextrine by the addition of 
water and the presence of concentrated sulphuric acid. 
When the Conferva is heated with hydrochloric acid of the 
usual strength, the cell-wall swells up and splits into separate 
fibres, the diameter of these being less than xqUo ^ 
limetre. They often appear as long as the cell, and lie side by 
side in the direction of the length of the cell ; no spiral arrange- 
ment or crossing of these fibres could be observed. The walls of 
many cells, which consist of cellulose, become split up into such 
fibres by boiling in hydrochloric acid ; this may be seen very 
plainly in the bass-fibres of flax, and a splitting-up of this kind 
occurs in mechanical operations upon them, as in the manufac- 
ture of paper. The cuticle does not pass in between the conti- 
guous cells, so that the walls of the two cells are in immediate 
contact. 
The contents of the cell consist at first of a gelatinous mass, 
coloured green by chlorophylle; the green colouring matter, which 
forms but an insignificant proportion of the w^hole, is dissolved on 
the addition of hydrochloric acid, and the gelatinous mass con- 
tracts. Iodine colours the mass brown, and then denser masses 
(nuclei), which lie irregularly scattered through it, become more 
evident. It withstands the action of sulphuric acid longer than 
the cellulose ; heated with nitric acid and then saturated with 
ammonia, it gives the xanthoproteate of ammonia, and therefore 
consists at least in part of proteine compounds. 
At a certain epoch of the development the nuclei of the gela- 
tinous mass become opake and increase in diameter ; then starch 
can be distinctly detected in their interior by means of iodine ; 
in other Confervse, for instance in Spirogyra, these points, in 
which starch is sometimes formed, may be perceived more di- 
stinctly. Sometimes the green gelatinous mass lies closely ap- 
plied to the cell-wall in C. glomerata, and the whole cell is densely 
filled with it ; sometimes, and particularly in rapidly developing 
cells, a clear fluid lies between the gelatinous mass and the wall, 
and in this fluid sometimes occur particles in molecular motion ; 
spaces filled with clear fluid also occur in the interior of the mass, 
and are traversed by reticulated processes of the gelatinous 
matter. 
The author observed and determined the growth and multipli- 
cation of C. glomerata in cooperation with his assistant M. Lasch, 
