218 TOWARDS THE HUMAN FORM 



and die ; but our Ephemeridae, which inherited the earliest 

 forms achieved, after having attained their permanent form, 

 do not fly away until they have freed themselves of a light 

 envelope, which actually constitutes a final moult. We 

 may therefore ask whether the primitive Insects, arrived at 

 their adult form, were not still capable of growth and moulting. 

 In that case we must grant either that the wings were still 

 formed of living cells — whereas there is no living substance in 

 the wings of our present insects except in the muscles attached 

 to the base in order to move them — or else that the wings fell 

 off spontaneously, as is the case with Termites, where their 

 falling is prepared in advance by the formation of a rupture- 

 line at their base, but that they could be subsequently reformed 

 at each reproductive period. This would bring the Insects 

 thoroughly into line with the general rule. Is it not singular 

 that they should have only a few weeks to live after they have 

 attained maturity ? Many other animal organisms — the 

 lowly Worms, 1 Fishes, 2 and many Birds — display brilliant 

 colours or splendid ornaments during the mating season. 

 Sometimes the eyes enlarge, the organs of locomotion are 

 perfected, the creature becomes more agile, and all the dis- 

 tinguishing marks of this season constitute their bridal apparel. 

 It is just in characters of this kind that the adult Insects 

 differ from their larvae. Is not the definitive stage just the 

 mating apparel that the insect of to-day only puts on once, 

 but which their ancestors displayed at each period of repro- 

 duction ? We are justified in asking this question since the 

 larger Crustaceans can reproduce themselves several times. 

 The duration of life in an adult Insect can be prolonged, 

 moreover, if certain precautions be taken. Labitte has kept 

 the beetle, Blaps, alive for more than eight years. 



We need say little of the Worms which have left evident 

 traces (Nereites, Arenicolites, Scolithus, etc.) in the tracks of 

 their bodies imprinted on sand, or mud, in the holes where 

 the}'' lived, or else material remains such as mandibles. 

 Among these there are still Eunicidae and Amphinomae, 

 which attain a great size, as much as two metres in length 

 and four centimetres in width. It is also possible that the 



1 Syllids (Autolytus, Myrianis, etc.), Nereids (Nereis cullrifera), 

 Phyllodocids, Cirratulids. 



2 Macropods of China, Sticklebacks, Minnows. 



