62 Laboratory Guide in Zoology 



in the scale of classification than the lobster ? Does it 

 show greater differentiation in its structure ? 



THE CYCLOPS 



The Cyclops is a microscopic crustacean of the same 

 class to which the lobster belongs. It may be found in the 

 water of almost any aquarium where aquatic plants have 

 been growing ; it appears to the naked eye as a small white 

 speck swimming rapidly about with a peculiar, jerky move- 

 ment. The large specimens usually found are females. 

 The males are much smaller, and generally are less abun- 

 dant, and therefore are not so well adapted to study. Pre- 

 paratory to a study with a low power, several specimens 

 should be removed from the culture jar to a watch glass. 

 To do this, place a finger on the end of a short glass tube, 

 and inserting the other end in the water as near the speci- 

 men as possible, remove the finger; the animals will be 

 drawn into the tube with the surrounding water, and by 

 again covering the exposed end of the tube they may be 

 transferred to a watch glass. If a little ether is placed in 

 the water containing the animals, their rapid actions will 

 be checked, giving a better opportunity for observation. 

 Place the watch glass on the stand of the microscope and 

 study with the low power. 



I. — Dorsal View. By careful manipulation, find a specimen 

 showing a good dorsal view. Observe the oval body, 

 tapering rapidly toward the posterior end. Study the 

 segmentation of the body axis; since the head and 

 thorax are united, as in the lobster, the body axis may 

 be divided into the two great divisions, — the cephalo- 

 thorax and abdomen. The cephalothorax is composed 

 of the first five segments beginning with the anteriqr 



