DISCOVERY OF THE CELL. 28 
parts of plants. How growth and multiplication took place, and where exactly the 
seat of a plant’s life lay, remained, of course, obscure. It was, however, natural to 
assume that the walls of these small cells constituted the essential part and living 
substance of plants, that they drew materials from the fluids which rose by suction 
in the tubes, and so increased in size and were renewed. 
It was as yet hardly suspected that the slimy substance which filled the cells 
of a plant, like honey in a honey-comb, was the basis of life. The observation made 
again and again at the beginning of the nineteenth century, that the cell-contents 
of certain algze are extruded in the form of globules of jelly, and that each globule 
moves independently and swims about in the water for a time, but then comes to 
rest and becomes the starting-point of a new alga, might undoubtedly have led 
to this conclusion. The accounts of these occurrences were, however, considered 
incredible by the majority of contemporary observers; and it was not till recently, 
when Unger established the phenomenon as an indubitable fact, that a proper 
estimation of its value was accorded. In the year 1826 this botanist investigated 
under the microscope a water-weed found at Ottakrinn, near Vienna, which had 
been described by systematic writers as an alga, and named Vaucheria clavata. 
To the naked eye it appears like a dense plexus of dark-green irregularly branched 
and matted filaments. These filaments, when magnified, are seen to be tubular cells 
which wither and die away at the base whilst growing at the apex, and developing 
sac-like branches laterally. (Pl. I.) The free ends of these tubes are blunt and 
rounded. The substance they contain is slimy, and, though itself colourless, is 
studded throughout with green granules; whilst near the blunt end of each filament 
these green particles are so closely packed that the entire contents of that part 
appear of a dark-green colour. 
Now, there comes a time in the life of every one of these filaments when its 
extremity swells and becomes more or less club-shaped. The moment this occurs, 
the dark-green contents withdraw somewhat from the extremity, leaving it hyaline 
and transparent. Almost simultaneously the contents of the swollen part of the 
tube nearest the apex become transparent, whilst further down the colour becomes 
very dark. (Pl. L, fig. a.) Twelve hours after the commencement of this change, 
that portion of the tube’s contents which occupies the club-shaped end separates 
itself entirely from the rest. A little later, the cell-wall at the apex of the tube 
suddenly splits, the edges of the slit fold back, and the inclosed mass travels 
through the aperture (fig. e). This jelly-like ball, having a greater diameter than 
the hole, is at first strangulated as it struggles forward, so that it assumes the shape 
of an hour-glass and looks for an instant as if it would remain stuck fast. There 
now arises, however, in the entire mass of green jelly an abrupt movement of 
rotation combined with forward straining, and in another instant it has escaped 
through the narrow aperture and is swimming freely about in the surrounding 
water (fig. d). The entire phenomenon of the escape of these bodies takes place 
between 8 and 9 A.M., and, in any one case, in less than two minutes. When free, 
each individual assumes the shape of a perfectly regular ellipsoid (fig. d), having 
