REGENERATION IN CAMBARUS. 30 1 



results. Young specimens of Cambarus (Bartonius) bartoni Fabr., 

 probably at the beginning of their second and third years were 

 taken on March 24, 1907, from a small stream which crosses the 

 Bryan Station pike about three fourths of a mile northeast from 

 the city limits of Lexington, Ky. The specimens used are not 

 like the typical C. bartoni of the eastern United States, but have 

 a narrower areola, less spiny carpus, and a shorter but broader ros- 

 trum than the eastern form. Dr. Ortmann states that they agree 

 with specimens described by W. P. Hay in the 2Oth Ann. Report 

 of the Ind. Geol. Survey, 1895, after comparing the living, speci- 

 mens with those in the Carnegie Museum from Mitchell, Lawrence 

 Co., Ind. 



Each specimen was put into a tumbler with water not quite 

 sufficient in amount to cover it. A small piece of mica schist 

 coming not quite to the surface of the water, was placed in each 

 tumbler so that the crayfishes could crawl upon it and expose 

 themselves to the air at will. The tumblers were kept nearly 

 covered by glass plates to prevent accidental desiccation. Care 

 was taken not to cover the dishes entirely, as the air was found 

 to become overcharged with carbon dioxide in a short time if so 

 covered. The water was changed completely three or four times 

 per day, and even oftener on very hot days ; for crayfishes seem 

 unable to endure warm water for any great length of time. 



The water used in these experiments was supplied by the city 

 water works of Lexington. This water is filtered through large 

 Jewell filters before being pumped into the water mains, and is 

 exceptionally pure. The complete change of such water every 

 few hours rendered the multiplication of bacteria or growth of 

 other fungous plants rather difficult, and tended to prevent the 

 accumulation of any sediment. 



When it appeared that any fungous growth was forming upon 

 the appendages and about the thoracic region, each crayfish was 

 treated for a few minutes with a bath of copper sulphate. The 

 vessels and stones kept in them were occasionally treated with the 

 same solution. The copper sulphate was used with a strength of 

 one part to a million, when the animals could be left in it for 

 some time. Solutions much stronger than this, one part in ten 

 thousand, can be used for a few minutes at a time with entire sue- 



