292 LAMARCK, His LIFE AND WORK 
because the subtile ambient fluids, penetrating by the 
alimentary canal, and being expansive, have been able, 
by an incessantly renewed repulsion from the centre 
towards every point of the circumference, to give 
rise to this radiated arrangement of parts. 
“It is by this cause that, in the Radiata, the intes- 
tinal canal, although still very imperfect, since more 
often it has only a single opening, is yet compli- 
cated with numerous radiating vasculiform, often ram- 
ified, appendages. 
“It is, doubtless, also by this cause that in the 
soft Radiates, as the medusa, etc., we observe a con- 
stant isochronic movement, movement very probably 
resulting from the successive intermissions between 
the masses of subtile fluids which penetrate into the 
interior of these animals and those of the same fluids 
which escape from it, often being spread throughout 
all their parts. 
“We cannot say that the isochronic movements 
of the soft Radiates are the result of their respiration ; 
for below the vertebrate animals nature does not 
offer, in that of any animal, these alternate and 
measured movements of inspiration and expiration, 
Whatever may be the respiration of Radiates, it is 
extremely slow, and is executed without perceptible 
movements ” (p. 200). 
The Influence of Circumstances on the Actions and 
Flabits of Animals. 
It is in Chapter VII. that the views of Lamarck 
are more fully presented than elsewhere, and we 
therefore translate all of it as literally as possible, 
so as to preserve the exact sense of the author. 
“We do not here have to do with a line of argu- 
ment, but with the examination of a positive fact, 
which is more general than is supposed, and which 
