PROGRESS IN BIOLOGICAL INQUIRIES, 1924 33 



State in establishing in certain rivers areas that should be closed for 

 a period of years in order to restore their mussel life. 



The experiments in rearing mussels in troughs was undertaken 

 on a larger scale than previously, and 100 new troughs were added 

 to the 4:2 already installed. The new troughs were not given the 

 protection of a shed, however, as was the case with the original 

 troughs. The original troughs produced 160,000 young mussels, 

 while, owing apparently to the exposure and consequent overheating 

 in the sun, production in the new troughs was a total failure. This 

 and other defects in the installation of the troughs and the conduct 

 of the experiments have been remedied and the work is being re- 

 peated. If this method can be perfected it is believed that it will 

 prove of great importance. 



During the summer Dr. L. B. Arey, temporary investigator, con- 

 tinued his study of the normal cyst and of the immune cyst, and the 

 relationship between mussel embryo and host fish. 



The mussels retained at the station become infected with a ciliate 

 (Conchopthirius), referred to in the repoit of last year. This 

 ciliate invades the marsupia of the mussels and destroys numbers of 

 glochidia. It is thought that the presence of this ciliate may be 

 consequent on a polluted condition of the water, due, perhaps, to 

 the increasing amount of seAvage entering the Mississippi above 

 Fairport from Davenport, Rock Island, and Moline. If this proves 

 to be the case it may be anticipated that the increasing amount of 

 sewage in the river will mean increasing difficulty in handling mus- 

 sels at the station. It is quite possible that this ciliate may seriously 

 affect the culture of mussels in troughs at this station by destroying 

 the juveniles as soon as dropped. Owing to these conditions it is 

 believed that the station's contributions to the aid of the mussel 

 industry must come through surveys, with the recommendations 

 resulting therefrom, and the various studies made largely by tem- 

 poraiy workers in the ecologj^^ and life history of the commercial 

 species. 



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 extended. The work has been done under 

 the general direction of S. F. Hildebrand and the immediate super- 

 vision of Charles Hatsel, acting director of the Beaufort laboratory. 



Thirty lots of diamond-back terrapin are now on hand. These 

 lots represent terrapins of different ages, or terrapins of the same 

 age which have been or are now being treated differently, and each 

 lot in itself or in combination with other lots represents an experi- 

 ment. All terrapins noAv on hand, except two lots, have been 

 hatched in captivity, and several of the lots represent terrapins of 

 a second generation that are being grown in confinement. 



The experiments under way include tests of the longevity of the 

 diamond-back terrapin, a determination of the age at which repro- 

 duction ceases, selective breeding experiments, the results of hybrid- 

 izinfr the North Carolina with the Texas terrapin, the value of winter 

 feeding in a hothouse, the natural sex ratio in terrapins, the neces- 

 sary number of males to a given number of females to produce 



