THE REPAIR AND REBUILDING OF THE LARVAL 

 CASE OF PLATYPHYLAX DESIGNATUS 

 WALK. (PHRYGANID). 



WM. S. MARSHALL AND C. T. VORHIES. 



The larvae of Platypliylax designates l are found abundantly in 

 a group of springs in the vicinity of Madison, and, being easily 

 obtained at any time during the year, have been collected for 

 work in the laboratory. Experimenting with a few larvae which 

 we kept in small aquaria, we noticed that those which had been 

 removed from their cases constructed new ones and also that 

 injuries to the cases, by removal of some part, were generally 

 repaired in a short time by the larvae. This led us to carry on 

 a number of experiments to determine how far injured shells 

 would be repaired by the larvae, and, if certain parts of the cases 

 were more frequently and readily rebuilt than others. 



The springs in which these Phryganid larvae live remain open 

 all the year ; this was a great advantage to us in that material 

 could be readily obtained throughout the winter. The water in 

 the springs is very cold during the summer as well as in the 

 winter months and the larvae, being accustomed to very cold 

 water, would not live, during the summer, in aquaria kept in the 

 laboratory or out of doors. We found it advisable to carry on 

 our experiments during cold weather, at which time it was easy 

 to keep the aquaria in cool places, bringing them into the labora- 

 tory only when our specimens were examined. In the autumn 

 and in the spring, just before or after freezing began or ceased, 

 we found the most convenient times for our work, as at these 

 periods of the year the aquaria could be kept on a ledge outside 

 of the laboratory window. 



The cases of the larvae of Platypliylax designatns are con- 

 structed, with few exceptions, from the sand which covers the 

 bottom of the springs in which they live. Irregularities in the 

 size of the sand grains used are sometimes observed, but there 



1 The identification of the species was made by Mr. C. Betten. 



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