A comparative study of nitrogen excretion in twenty-three cockroach species.

-l. Nitrogen and cation excretion/storage in 23 cockroach species representing I l subfamilies have been examined. Measurements of externally excreted ammonia nitrogen, uric acid nitrogen, total nitrogen, potassium and sodium were made. Values of total body nitrogen, body urate nitrogen, and body potassium and sodium are also reported. 2. A significant correlation was found between body nitrogen and body uric acid nitrogen. Certain species contained very high levels of uric acid/urates representing as much as 72% of their total body nitrogen. Contrarily, other species were found to contain low levels of uric acid/urates, representing as little as 3% of their body nitrogcn. 3. A less significant correlation was found between internal nitrogen storage and external nitrogen excretion. Certain species can be classified as uricotelic, since as much as 62% of their total fecal nitrogen may be excreted as uric acid-nitrogen. Other species can be designated as ammonotelic, since they may excrete as much as 70% of their total fecal nitrogen as ammonia nitrogen. 4. Increased body nitrogen retention may be correlated with increases in body potassium and/or sodium. The internal storage of nitrogen as uric acid appears to involve the formation of potassium and/or sodium urate salts.