THE LOWER FORMS OF LIFE. 105 



When first separated they have the appearance shown at Fig. 141, 

 but speedily appear as at Fig. 142, with their umbrellas and tentacles, 

 and grow up gradually until they attain the form and size described 

 and illustrated in the last chapter. 



Such are some of the remarkable facts connected with the repro- 

 duction and development of the Hydrozoa. M. A. De Quatrefages, 

 in an admirable little book, " The Metamorphoses of Man and 

 Animals," which has been well translated by Dr. Lawson (Hard- 

 wicke), goes fully into the curious subject of alternation of genera- 

 tion, and concludes his fourteenth chapter in the following words : 



" What would our readers think were we to express ourselves 

 thus ? A butterfly deposits an egg from which springs an earth- 

 worm that is soon converted into a caterpillar. From this cater- 

 pillar a series of buds are produced which become so many indi- 

 viduals like the first one ; then each of these, although preserving 

 the caterpillar head, assumes the body of a chrysalis ; this body is 

 constricted at intervals, and gradually becomes converted into a 

 cluster of butterflies piled up one upon another; the caterpillar head 

 then falls off, and the butterflies fly away one by one. At first they 

 resemble moths, but by degrees they assume their true characters, 

 and become beautiful diurnal Lepidoptera. Who would put any 

 trust in a history which described a series of transformations as 

 fantastic as those seen in a dream? Yet change a few of the 

 expressions, employ the terms Acalephae, and Medusas for those of 

 insects and butterflies, and that which a moment before had been 

 fiction becomes simple truth." 



CHAPTER VI. 



THE ACTINOZOA. 



THE Actinozoa form the second division of the Coalenterata, and 

 they are at once and definitely distinguished from the Hydrozoa by 

 possessing a stomach which is freely suspended in the body of the 

 animal ; whereas, as I have already pointed out, this organ in the 

 Hydrozoa is merely hollowed out, as it were, in the substance con- 

 stituting that creature's corporeal structure. This is not a mere 

 fanciful distinction raised up by arbitrary classifiers to make their 

 arrangements more definite ; it is a great step in the upward 

 progress of the living being towards that perfection of structure 

 which we see in man and the higher animals. I dot down the 



