80 



plankton work. The total number of samples for sanitary analyses collected 

 at the station and shipped to Champaign during the two years is two hundred 

 and eighty. As these analyses include the determination of the free and 

 albuminoid ammonia, the nitrites and nitrates, the chlorine, and the oxygen 

 consumed, they will furnish data of grgat value for a comparison with those 

 derived from the plankton work. 



The shipment of samples to Champaign for an analysis of the gases dis- 

 solved in the water was begun July 23, 1897, samples being sent from the 

 surface water of the river for the determination of the oxygen. In August 

 fortnightly surface samples from Thompson's and Quiver lakes were 

 added to the shipments, and in- November additional samples were 

 sent from each of these localities for an analysis of the carbon dioxide. 

 With the beginning of 1898 samples were collected frou both the 

 surface and the bottom waters of the three localities above mentioned 

 for the determination of both the oxygen and the carbon dioxide. 

 This involves the collection and shipment of eight bottles of water from each 

 of the three stations— a total of about nine hundred and fifty samples being 

 shipped in 1897 and 1898. The water was collected with the plankton pump 

 by means of a small pet cock inserted in the discharge pipe. A rubber tube 

 if fastened upon this and inserted in the bottle and water sufl&cient to fill the 

 bottle three times is pumped through it. The bottle is then closed, the 

 sample being collected with a minimum contact with the air. If the change 

 in the water between the time of collection and the time of analysis does not 

 vitiate the results, we shall find these gas determinations of great importance 

 in the discussion of the plankton data. 



The equipment has been maintained in first-class condition so far as the 

 wear and tear of property subject to the vicissitudes of an aquatic environ- 

 ment will permit. The hull of the laboratory boat has been provided with 

 salt shelves and its bottom thoroughly salted to insure its preservation. The 

 dejks and guards have been painted repeatedly, and the canvas roof has re- 

 ceived a heavy coat of paint. The floors have also been treated with several 

 coats of oil. Three years' experience in our floating laboratory has only 

 increased our satisfaction with its fitness and convenience for the work of a 

 biological station. 



The steam launch, with the new equipment of machinery described in the 

 last report, has been of great service. A few repairs have been made from 

 time to time upon the engine, and the boiler and stack have been provided 

 with a shield to decrease heat in the launch. New tubes have also been 

 placed in the boiler. In 1897 the steamer "Josie Sivley" collided with the 

 "lllini" while she was at ancher on the river front, and crushing her against 

 the guard of the laboratory boat opened a seam up the larboard side and 

 broke several ribs and a staunchion. The launch sunk in shoal water and 

 was easily raised, the damage being subsequently thoroughly repaired. In 

 the spring of 1897 Mr. Newberry secured an engineer's license, and has since 

 cared for the launch. 



During the session of the summer school the carrying capacity of the 

 launch is severely taxed in providing transit for the tield excursions of the 

 classes. At no time is the speed very great, seven miles an hour being the 

 maximum maintained. Furthermore, the draught of the boat interferes with 

 its greatest usefulness in the shoal waters in which at times our work compels 

 us to go. It is only a question of time when extensive repairs will be neces- 

 sary upon the hull. I would therefore recommend that an effort be made to 

 secure a larger boat with more powerful machinery so as to carry more pas- 

 sengers and, if necessary, to tow a barge. Greater speed and less draught 

 can be secured with such a boat. It would also enable us to considerably ex- 

 tend the field of our operations. Such a launch will be a prime necessity 

 when the work of the station is extended to the Mississippi river. 



The outfit of small boats, which consist of two lap-streak lake-boats, one lap- 

 streak river boat, and an Illinois river skiflf, has been supplemented^ by the 

 addition of a large flat-bottom seine boat twenty feet in length with five-foot 

 beam for the plankton work. The increasing complexity of this work and the 

 variety of apparatus necessary for its performance nas made the load required 



