Howard. — The Catfish as a Host 69 



glochidial shell. Eight out of eleven fish examined were 

 infected and the maximum infection observed (on one 

 fish) was twenty-one. 



The results would seem to demonstrate Ictalurus punc- 

 tatus as a natural host for Quadrula pustulosa and the ex- 

 periments so far as they have gone would indicate that 

 other species of catfish may be also. The possibilities of- 

 fered by the catfish as a medium for artificial propagation 

 are obviously almost ideal. This fish, valuable for food, is 

 abundant and can be transported and handled with less 

 mortality perhaps than any other species. These conditions 

 make the expense of propagation less and the chances of 

 successful distribution in every case greater. 



Summarizing the practical results we find the investiga- 

 tion has provided a species of mussel and a species of fish 

 not hitherto available for artificial propagation. 



DISCUSSION 



Dr. R. E. Coker, Fairport, Iowa : We at Fairport, Iowa, are en- 

 gaged in the propagation of the freshwater mussels which support the 

 important industry of button manufacture. The fishing has been so 

 extensive as to deplete the more important rivers of the country, until 

 the point is now reached where we have to replenish the beds. The 

 method of doing so is this. We take the young stage of the mussel 

 (the glochidium) and get that infected on the gills of the fishes; then, 

 after a certain period of time, or right away, as the case may be, these 

 fish are released in the streams, and the mussels in due course, after 

 the necessary period of parasitism, fall to the bottom, where they can 

 look after themselves. All fishes are not equally susceptible to the 

 mussels ; there are some which we cannot now use at all, but the game 

 fishes can all be used to carry mussels of the Lampsilis group, and 

 other species of economic importance. There is another group of 

 mussels generally included under the genus Quadrula which yield a line 

 quality of button. Up to the present time we have not been able to do 

 anything with that group of mussels. We now handle lots of others, 

 but not those. Up to this time, also, we have had no use for the cat- 

 fish, and a great many other of the coarse fishes. So when we seined 

 out the overflow ponds and sloughs we could use the game fishes but 

 had to discard the catfishes. 



This paper by Dr. Howard shows some results of the work which 

 he lias been carrying on with reference to the quadrulas, mussels which 



