178 EVENINGS AT THE MICROSCOPE. 



rounding water finds its way in currents, bringing oxygen 

 to be respired and food to be devoured. 



The translucent shell descends in front into a sharp 

 long beak, below which are seen the organs of the mouth, 

 two pairs of foot-jaws, beset with fine bristles. At the 

 origin of the beak is the eye, consisting, as we saw in the 

 Cyclops, of several lenses, enveloped in a common cornea, 

 the whole forming a movable orsfan of a blue-black hue. 

 Just behind this, at the very highest part of the shell, 

 is a little colourless bladder-like vesicle, which constantlv 

 maintains a rapidly alternate contraction and dilatation. 

 This is the heart, and this motion circulates the blood. 



Below this, there is seen a great translucent irregular 

 mass of fle^h, evidently comprising many viscera, which 

 winds along from one end of the shell to the other, nearly 

 occupying its entire area. It is not in connexion with it at 

 the hinder part, as we see by its free movements there, 

 where it curves round, and, bending beneath, terminates 

 in a blunt tail, armed with two strong hooks, which can 

 at pleasure be thrust down through the narrow orifice of 

 the shell, and become partially straightened by being 

 forcibly thrown backward. This great central mass is 

 mainly occupied by the alimentary canal, in which food 

 in various stages of assimilation may at all times be seen, 

 and in which the interesting function of digestion can 

 be witnessed throughout, from the first seizure of the 

 atom and its mastication by the jaws, to the discharge of 

 the useless remains. 



The individual before us does not carry at this time 

 eggs in the process of development ; but the deficiency 

 is supplied by a Daplinia which is playing about in the 

 same drop of water. Here you perceive, between the 

 arched outline of the shell and the sinuous outline of the 

 free soft body, an open space of some size, which con- 

 stitutes a receptacle, in which the eggs are deposited as 

 they are laid, and in which they remain not only until 



