Corwin. — Raising Freshwater Mussels 309 



in that they had dropped all the young mussels except a few 

 scattered ones; but from each several lively infant luteola 

 could be obtained. For pike perch Nos, 6 to 10, inclusive, 

 this was 273 days after infection. The temperature of the 

 lake water on June 3d was 67 degrees F. 



Since the fishes at Homer station were carrying approxi- 

 mately the original infection as late as May 3d and those in 

 the lake were about free from glochidia on June 3d, it appears 

 that the month of May is the time when pike perch, infected 

 as late in the summer as August 19th and September 4th of 

 the previous year, drop the larval mussels. 



AVERAGE NUMBER OF JUVENILES PER FISH 



Attempts to determine the average number of juvenile 

 mussels per fish host have resulted variously. In previous 

 years it was suspected that the larval mussels were devoured 

 by enemies, or, on dropping from the host, were swept out of 

 the enclosure by waves. The outcome of one experiment 

 this year was significant. Two enclosures, each 10 feet 

 square and 9 feet high, were made, one with sides of galvan- 

 ized wire screen of 12 meshes to the inch, the other with 

 sides of 1-inch mesh poultry netting. These enclosures or 

 pens were placed in the same locality fifty feet apart. 



Of ten pike perch infected with Lampsilis luteola on May 

 21, 1920, five were placed in each pen. Both lots had 

 dropped the larval mussels, were free from infection and 

 were released alive at the same time. 



The enclosures were not disturbed until September 11, 

 1920, at which time they were brought to shore and their 

 contents examined. Few organisms, other than the young 

 mussels, were present on the bottom of either pen; hence 

 it is inferred that neither crop of mussels suffered greatly 

 from predaceous enemies. From the fine screen enclosure 

 were recovered 4,150 living juvenile Lampsilis luteola and 19 

 pairs of valves of dead luteola, making a total of 4,169, or 



