62 ANTENNA. 



is to be found in the fact that an antenna once 

 seriously mutilated never regains its normal number of 

 segments. Such, at least, has been my experience. 

 It is possible that very young specimens may have 

 more complete powers of reparation. I doubt very 

 much, however, whether it is so, because I have 

 observed in Chloeon {Ephemera) that the terminal 

 segments of the antenna, if once removed, are never 

 replaced (although the antenna continues to grow), so 

 that not one specimen in twenty of those which I 

 examined had perfect antennae when the insects were 

 half-grown. 



As illustrating the partial recovery which takes 

 place, I will take the following cases from my note- 

 book. 



On the 11th of April, I removed the terminal por- 

 tion of the right antenna of a pale Orchesella clncta, at 

 the middle of the second segment, as shown in 

 PI. LXII, fig. 1. On the following day the animal 

 moulted, and the mutilated antenna was as in fig. 2, 

 the second segment being a little elongated, but not 

 much altered, probably on account of the short time 

 which intervened between the mutilation and the 

 moult. On the 19th of April the antenna was as in 

 fig. 3, and consisted of three segments. The second 

 and third were quite unlike those of normal specimens, 

 the second being unusually large, and the third, which 

 is normally quite short, being elongated and somewhat 

 club-shaped. At the next moult both these segments, 

 and especially the third, elongated somewhat (fig. 4), 

 but they made no further approximation towards the 

 normal form. 



Again, on the 5th June, I treated another specimen 

 in the same manner, leaving the antenna in the state 

 shown in PI. LXII, fig. 5. On the 17th June it had 

 moulted, and was as in fig. 6. Here, the mutilation 

 having taken place near the extremity of the segment 

 and some days before the moult, it will be seen that 

 more change has taken place than in the preceding 



