172 REPRESENTATION OF THE 



seems to refer above, wlien he calls one of the generative 

 organs " a third zooid." 



§ 5. Another illustration of the semi-independent posi- 

 tion of the sexual organs is offered by some aberrant forms 

 of the Crustacean type, especially by species of Cirrhipedes 

 and Lerneans, which undergo what is termed a retrograde 

 metamorphosis. These species commence life as active 

 Entomostraca, but afterwards lose the power of locomotion, 

 attaching themselves to the integuments of marine animals 

 or to other bodies, while at the same time they become va- 

 riously transformed — or deformed, as we should say, in the 

 majority of cases — by the obliteration of certain parts of 

 the typical organization, and the disproportionate develop- 

 ment of the reproductive organs. Here the nature of the 

 change is such as to suggest doubts of the correctness of 

 the common view of the Entomostraceous stao^e beino- a 

 larva state, and the subsequent transformation, though of 

 a retrograde kind, one analogous to the metamorphosis of 

 an insect. Another view at least ma^/ be taken — namely, 

 that the transformation is a sort of gamomorphic alterna- 

 tion, the reproductive structures in many respects standing 

 more in the position of superadded sexual zooids than of 

 constituent organs. Prof. Owen ranks the case as one de- 

 cidedly of the nature of metagenesis,* and there is at all 

 events a much more complete change in the relations of 

 the parts than in any case of undoubted metamorphosis. "f* 

 The greater tendency of the males to retain their original 



* Partheuogenesis, p. 25. 



t The only cases in Insects whicli are at all similar are those before 

 referred to in the gregarious species, where the procreation of ova for the 

 whole community devolves on a single fertile female or queen. The 

 ovaries may then attain an enormous size, as happens most remarkably in 

 the queen of the Termites, whose abdomen at the time she commences 

 laying is from 1500 to 2000 times larger than the rest of the body, the 

 eggs being subsequently deposited at the rate of 80,000 a day for several 

 successive weeks. 



