2 DAVENPORT ACADEMY OF SCIENCES. 



reason to believe, in the light of recent experimental work, that 

 the psychical is a factor in the behavior at least of the higher 

 forms of unicellular animals; the discover}' of the relation of par- 

 asitic Protozoa to various diseases has opened up a broadening 

 field for the pathologist, and no doubt, in the future, questions of 

 sanitation involving the Protozoa will arise, as others have already 

 arisen, making a knowledge of the forms which inhabit the 

 sources of common water supplies, their life histories and the 

 means of successfully combatting them essential for the protection 

 of the public health. An acquaintance, therefore, with as many 

 species as possible, their structure and the conditions under which 

 they exist would seem to be quite desirable. 



From a purely sj'stematic point of view the one-celled animals 

 of this country have been neglected, only a few workers here and 

 there having devoted a portion of their time toward classifying 

 and working out the life histories of the .species in their immedi- 

 ate vicinities. 



The purpose of this paper is to furnish a preliminary report on 

 the species of Protozoa to be found in the waters of the state of 

 Iowa. It is an attempt to set forth, in as plain and concise terms 

 as possible, descriptions of species already known which inhabit 

 the waters of this state, also calling attention to certain forms 

 which apparenth' have been undescribed previous to this time. 

 Drawings of the species observed have been made either from the 

 living specimens or from permanent preparations, the former being 

 in most instances preferable and more accurate as even the best of 

 reagents may give to the delicate organisms a distorted and unreal 

 appearance. 



The entire state has not been covered in the preparation of this 

 paper although the waters of more than thirty counties compris- 

 ing the eastern, central, southern and extreme north-western por- 

 tions of the state have been examined. Observations have been 

 made over wide enough territory for us to conclude that the dis- 

 tribution of Protozoa in this state is quite general. For the most 

 part, species taken from Lake Okoboji were identical with those 

 found in the ponds, pools and small streams of the south-eastern 

 counties of the state and, with few exceptions, .species found in 

 other localities of the state have been obtained from the waters of 

 Johnson county where the greater part of the work for this paper 



