316 



EVENINGS AT THE MICROSCOPE. 



sions; and therefore I will merely say here that each one 

 of these tiny vesicles carries a barbed and poisoned arrow, 

 which can be shot forth at the pleasure of the animal with 

 great force, and to an amazing length; that hundreds are 

 usually shot together; and that this is the provision which 



the All-wise God has given to 

 these apparently helpless animals 

 for securing and subduing their 

 prey. 



There is, however, another 



organ still more conspicuous in 



our little Sarsia, of which I have 



not yet spoken. As the whole 



animal has the most absolute 



i transparency, we see that the 



\ roof of the bell is much thicker 



I than the sides, and that it graclu- 



j ally thins off to the edge. The 



i' interior surface is called the sub- 



i t 



S \ umbrella, and it carries within 



/ I its substance four slender tubes, 



/ j which, radiating from the centre 



i of the roof, proceed to the mar- 



• gin, where they communicate 



with another similar canal which 



runs round the circumference, 



/ 



sending off branches into the 

 tentacles. This is the circulatory 

 sabsia. system; and you may see, with 



the magnifying power which you 

 are at present using, that a clear fluid is moving rapidly 

 within all these canals, carrying minute granules; not 

 with an even forward current, but with an irregular 

 jerking movement, as if several conflicting eddies were 

 in the stream. Yet we discern that, on the whole, the 

 granules are moved forward; passing from the centre of 



