348 Illinois State Laboratorii of Natiinil History. 



METHODS OF CAPTURE AND STUDY. 



Piotifers should be widely studied, not only because they 

 are interesting but because they are so easily accessible to 

 nearly every one. Representatives of the group are found in 

 every pool, pond, river, or other body of water. They seem 

 to be little dependent upon the coarser aquatic vegetation, 

 since they are equally abundant in waters with or without 

 vegetation. No pond or mud hole is too insignificant to be 

 populated by some of these forms. If one wdshes to study 

 them at times other than their usual season, or desires to 

 have material for class use, all that is necessary is to collect 

 some of the bottom of a dried-up pond and keep it until ready 

 for the material. Then a small quantity may l)e put into a 

 glass jar with some filtered water, and in twenty-four hours 

 the forms will begin to appear. Such an aquarium may be 

 kept up almost indefinitely by placing it in a moderately 

 cool room in the sunlight, and renewing the water from time 

 to time as it evaporates. 



This work of starting aquaria from the bottom of dried-up 

 bodies of water should be extensively practiced, as the ob- 

 server will in this way meet many forms which he would not 

 otherwise find ; not only rotifers but numbers of Protozoa and 

 microscopic plants as well. 



Another method of obtaining material is to collect water 

 from various sources and start a number of cultures by plac- 

 ing small quantities of the water in watch-glasses, or other 

 small dishes, keeping a sharp lookout that the water does 

 not dry out. If these dishes are examined from time to time 

 they will be found to have developed certain forms of Protozoa, 

 one species or another predominating in each of the dishes. 

 After a time, if the student has ])een faithful, the chances 

 are that he will be rewarded by finding in several of the 

 dishes an almost pure culture of some particular species. 

 This method was tried by Prof. Frank Smith in the zoological 

 lal)orat()ry of the University of Illinois during the winter of 

 1894 with good results, pure cultures of Distyla oliioeiisls, 

 Hiidatina scuta, Steu.tor avridcHS, Stylonychia iiiytiliis, and 

 other species being obtained. 



