PROGRESS IN BIOLOGICAL INQUIRIES 55 



During the year the State of Washington published the results 

 of Mr. McMilli'n's investigations on the Washington coast. A report 

 covering the points discussed above is now nearing completion. 



FRESH-WATER MUSSELS 



Of immediate public interest probably the most outstanding in- 

 vestigation pertaining to fresh-water mussels made during the last 

 half of 1924 was the survey of Lake Pepin, a widened portion of the 

 Mississippi Eiver located between Wisconsin and Minnesota. This 

 survey indicated definitely the great value of giving four and five 

 year periods of rest from shelling operations to fresh-water mussel 

 beds, the population of which has become materially depleted. 

 The sections of Lake Pepin opened to sholling in 1924 after having 

 been closed four years seemed to have regained almost their full 

 original mussel population, although they were greatly depleted at 

 the start. Dr. R. E. Coker while connected with the bureau Avas 

 largely instrumental in promoting concurrent action by the two 

 bordering States that effected the closure of alternate sections of 

 Lake Pepin. The survey mentioned shows the wisdom of this 

 measure. 



After the system of closing alternate sections in Lake Pepin be- 

 came effective similar action was taken by several other States with 

 regard to their mussel areas. There are a number of States, how- 

 ever, that might also enact similar conservation measures to the 

 benefit of their mussel resources. 



Mussel surA^eys were also made of various other portions of the 

 Mississippi River. 



The culture of mussels in hatchery troughs was continued. 

 Several thousand young mussels were produced but no striking ad- 

 vance in mussel-cultural methods was made, although some negative 

 information was gained. Research work with regard to the food of 

 young mussels was continued during the summer of 1924 by Dr. 

 E. P. Churchill, of the University of South Dakota, who was em- 

 ployed as special investigator. An important line of investigation 

 with regard to the relation of fish slime to glochidial action was 

 beffun during this summer by an independent investigator, Dr. M. M. 

 Ellis, of the TTniversity of Missouri. 



TERRAPIN 



The experiments in the culture and breeding of diamond-back 

 terrapin, which have been conducted at Beaufort, N. C, for a num- 

 ber of years, have been continued with marked success. The work 

 is under the general supervision of Samuel F. Hildebrand and in 

 immediate charge of Charles Hatsel. No changes in the 30 lots of 

 terrapins used in the A^arious experiments haA^e been made since the 

 last report was published. 



The total number of young terrapins remoA'ed from the e<x<x beds 

 during the fall of 1924 A\'as 3,458. Of this number 2,406 Avere placed 

 in a hothouse, Avhere they are kept warm and will be fed throughout 

 the winter. Considerable progress has been made in the methods 

 of handling the terrapins in the hothouse. Growth has continued 

 and the death rate has decreased. 



