THE LARVAL CASE OF PLATVFHYLAX. 237 



The cut was now well opened daily for seven days. On each of 

 the first two days a distance of I mm. at the anterior end was 

 repaired, on the third and on the fourth days 2 mm., and on the 

 fifth and sixth days a distance of 4 mm. was repaired. The re- 

 pairing on the sixth day was very poorly and loosely done and, 

 no repair being made on the next, the seventh day, the experi- 

 ment was abandoned. 



The cutting: of the cases from end to end causes no inconveni- 



o 



ence to the larva and no exposure of its body. In all examples 

 cut it was difficult to see, without a fairly close examination, that 

 a cut had been made ; the firmness of the case causes the cut 

 edees to either touch along their entire distance or, in many 



t> o 



instances, to slightly overlap. The repair was always begun at 

 the anterior end, the larvae paying but slight attention to the 

 opposite end although, in a few cases, this was also repaired and 

 it may be, that if the cut cases had been in every instance left 

 unmolested for several days the ultimate result would, in all ex- 

 periments, have been a completely repaired case. The distance 

 of the repair at the anterior end represents the distance which 

 can be readily reached by the larva without turning in its case. 



NOTCHES CUT IN CASE AT ANTERIOR END. 

 These notches were cut in from the anterior margin of the 

 case and on its different surfaces ; the cuts were in general equal 

 in depth to one fourth or one fifth the length of the shell. While 

 not always of the same size and shape the piece removed was 

 generally very nearly 3 mm. in length and 2 mm. in width at its 

 base, the base of the triangular piece cut out being always along 

 the anterior margin of the case. 



1. Twenty-ninth, lateral notch cut; in two days this was half 

 filled with new sand grains ; the next six days no change. In 

 thirteen days the notch had been completely filled in and a few 

 grains added to the anterior edge. 



2. Dorsal notch cut, was completely repaired in two days. 



3. Dorsal notch cut and partially repaired by following day; 

 in building a small opening was left by the larva at the apex of 

 the notch and this was never repaired. In two days the anterior 

 margin was built even to rest of case. 



