CULTURE OF FRESH-WATER MUSSELS. 83 



to find that they, like adult mussels, were usually buried in the mud, a small portion 

 only of the posterior end of the shell reaching the surface. In fact, the only exception 

 observed was in a case of interference with the water supply coming to the mussels, a 

 discussion of which will be taken up later. No evidence of migration, by tracks or 

 other signs, was seen. It would seem, therefore, that for this species when on a mud 

 bottom the byssus would serve chiefly as an anchor for emergencies and would not 

 frequently be called into service (cf. Isely, 191 1). A change of position in the mud was 

 noted when, owing to the presence of a small catfish that had escaped from another 

 basket, the mussels burrowed deeper. 



At the time of removing the mussels from the river for the winter the basket con- 

 taining the brood of Lampsilis luteola was placed in a tank and the fresh supply of water 

 cut down; then the mussels began to migrate, as can be seen by their tracks in the 

 photograph (fig. 75). When the water was entirely drawn off, those on the surface fell 

 over and closed their shells. 



Altogether by observations for such brief periods the author did not note a varied 

 number of locomotor reactions. The fact is, mussels when thriving and undisturbed 

 seem to be comparatively inactive. Experimentally, doubtless, there would be a 

 varied number of reactions depending upon the variety of stimuli applied. At present 

 in our campaign to preserve the mussels and to increase their numbers we are particu- 

 larly interested in the reactions manifested under natural conditions. We have some 

 evidence of adaptations to depth of water and migration determined by river stages. 

 There are indications also that some breeding reactions are influenced by light, others 

 by temperature, chemical action, etc. The reactions of mussels when caught on sand 

 bars by receding water vary with the species. The hieroglyphics of their wanderings 

 under these conditions are sometimes very elaborate. 



The discovery that the parasitism of mussels is limited in some species to one or a 

 few species of hosts suggests the possibility of specific reactions in these by means of 

 which the infection of the host is insured. (Howard, 1914a, Conditions of Infection in 

 Nature, p. 39). This particular phase of their habits did not come within the range of 

 this investigation, but it is suggested that in these ecological relations of parasitism the 

 student of animal behavior may find that the ordinarily inactive fresh-water mussel will 

 furnish a varied and interesting subject for study. 



DISCUSSION AND APPLICATION OF RESULTS. 



In considering the results of the foregoing experiments attention is directed particu- 

 larly to those which seem applicable immediately to the campaign for mussel conser- 

 vation. 



Prof. J. L. Kellogg (19 10) points out that there can be practically no conservation 

 without culture or cultivation. Extinction has been the unvaried fate of useful forms, 

 plant or animal, where the natural supply has been depended upon. In the more 

 primitive human societies all food is obtained from the public domain, but civilization, 

 with increase of population, has survived by assigning individual property rights from 

 the public domain, thus encouraging and making cultivation possible. To give an 

 example in a field closely allied to that of fresh-water mussels, this principle has been 

 strikingly illustrated in the history of the oyster and clam fisheries. Those States, as 

 Rhode Island and Connecticut, which framed laws encouraging the culture of oysters 



