206 EVENINGS AT THE MICROSCOPE 



all its limbs, for the purpose of progression, and also for 

 the creation of currents in the fluid, which currents sub- 

 serve a double object the bringing constant supplies of 

 water to be respired, and floating atoms of food to be 

 devoured. 



In this individual, which is a female, the antennae are 

 nearly equal in size throughout their length; but in the 

 male, the middle joints of the upper pair are remarkably 

 enlarged, forming a large swelling, followed by a sudden 

 contraction, the first part of which is hinged. All of the 

 true feet, and the second pair of foot-jaws, are divided to 

 the base into two equal branches, so that the animal seems 

 to possess no fewer than twenty-six limbs, each of which 

 being many-jointed, and each joint, as I have observed, 

 being set with delicately plumose hairs, the whole effect 

 is most elegantly light and feathery. 



On each side of the slender tail (more correctly, the 

 abdomen) you see an oval bag connected with the body 

 by an excessively slender thread of communication, and 

 filled tensely with pellucid globose bodies. Like John 

 Gilpin, of equestrian fame, when 



"He hung a bottle on each side 

 To keep his balance true," 



our little natatory harlequin "carries weight." But these 

 bags are filled with eggs, a temporary provision for their 

 due and proper exposure to the water, while yet they are 

 protected from enemies. They are developed only at cer- 

 tain seasons, when the eggs, having attained a given amount 

 of maturity in the ovary, are transferred through the ex- 

 ceedingly slender tube into these sacs, and are there car- 

 ried about by the mother until the young are hatched, 



