THALLOGENS. — 227 
tible spontaneous movement. “ In order to observe this phenomena 
properly,” says M. Thuret, “the most simple means is to arrange 
some freshly-gathered specimens in a plate filled with water. In 
two or three days the external pelicule will burst, and the chaplets 
will spread themselves over the water. If recourse is then had to 
a microscope, it will be seen that the chaplets, originally very long 
and contorted in a thousand ways, are divided into numerous frag- 
ments of unequal length, nearly all straight, or only slightly 
flexuose, moving themselves in the direction of their length, and 
seeming to creep upon the plane of the object plate. Their pro- 
gress is slow, but very perceptible. If the observations are con- 
tinued during some days, the chaplets will become immovable, in- 
crease in size; at the same time a mucilage is developed by which 
they are surrounded as in a transparent frame: Sometimes the 
seeds considerably enlarge and divide themselves, so as to form two 
others, but laterally ; this formation repeats itself many times, and 
it would seem natural to seek there for the origin of new chaplets. 
Unfortunately, the increase of the seeds in number, by diminishing 
the transparency, no longer permits us to follow their increase 
with the same facility.” 
- It is obvious, then, that these plants present an organisation 
quite rudimentary, and that their mode of reproduction consists 
of a species of segmentation, namely, the division of the individual 
into new individuals, an arrangement which seems to approach the 
a. of the lower animals rather than that of the vegetable 
world. 
The NVostoc—in consequence, no doubt, of the extreme rapidity 
of its vegetation—greatly attracted the attention of the alchemists, 
Who often mention it, and it enters into many of their recipes for 
the pretended transmutation of metals. 
: Spheroplea annulina, belonging to the sub-family Oscillatoride, 
1s a freshwater species, belonging to the Confervacex, composed o 
ong filaments, formed of cellules more or less elongated, -and 
associated end to end like the Nostocs. Thesercells consist in their 
adult state of Chlorophyle, a watery liquid, and some feculous 
8ranules ; the whole distributed in such a manner that the liquid 
element forms coarse cells, arranged in straight lines. (Fig. 300, 1). 
Thus the P rotococcus is an individual consisting of one cell only. 
Qa 2 
