142 AQUATIC MICROSCOPY FOR BEGINNERS. 



the aquarium and for the purpose of examining their 

 stems and leaves for the microscopic animals which 

 they may be carrying, he should not lift them from the 

 water, since that movement often dislodges the adhe- 

 rent creatures, washing them away beyond recovery. 

 A better plan is either to scoop a mass of plants into 

 the dipper, there selecting the parts desired, throwing 

 out those discarded, ar^d gently pouring the water and 

 the acceptable portions into the waiting bottle; or the 

 wide-mouthed vessel may be partly submerged and 

 the plants gently floated into it. The former plan is 

 perhaps the better, since any animals that may be 

 washed from their moorings will remain in the dipper 

 and be transferred with the water to the collecting-jar. 

 No pond whose surface is mantled by a layer of 

 Lemna should be passed without a sweep of the dipper. 

 The little fronds and their delicate rootlets harbor 

 many a curious creature. No slow stream where My- 

 riophyllum abounds should be neglected. Those 

 feathery leaves are the favorite resorts of sedentary 

 Infusoria, Rotifers, and agile Entomostraca. The 

 hornwort (Ceratophyllurii) is likely to prove a valuable 

 acquisition, but one that is usually less abundantly 

 productive of microscopic supplies than Myriophyllum. 

 Utricularia may also be examined with some proba- 

 bility of success, although it is usually the most disap- 

 pointing of all the water-plants with divided leaves, 

 probably because it has itself the habit of feeding 

 upon any small animals that may venture too near that 

 valvular entrance to its utricles. . Anacharis Canaden- 

 sis, "water-weed," as it is often called, is not usually 

 a good hunting ground for sedentary Infusoria, neither 

 is the lower surface of the water-lily l.eaves. Both are 



