76 Traces of Unity 



animal. The Mammillaria nivea v. cristata, might 

 easily be mistaken for a brain-madrepore ; the Monsonia 

 Burmanii is the image of an ordinary coral ; and the 

 Rhipsalis copies not less closely the Isis hippuris, and 

 other articulated corals. Indeed it is quite conceivable 

 that in some of these cases plant and animal might be 

 confounded if they were seen lying together on the sea- 

 beach, as might very well happen after a storm in many 

 parts of the torrid region of America. 



The acorn-shell (Balanus) has a multivalve shell in 

 which the valves are arranged in a whorl like the sepals 

 in the flower of the dove plant, and the resemblance to 

 this flower is further increased by the position in the 

 heart of the shell which is occupied by the body of the 

 cirrhiped, and by the way in which the shell itself, at 

 least in the mature condition is attached to some 

 foreign body. The wings and winged legs of the Mantis 

 siccifolia, or walking leaf, resemble shrivelled^ autumn- 

 stained leaves so closely that the insect may readily be 

 mistaken for an emancipated orchid-flower. The mussel 

 may exhibit in a fixed form a state of things which is 

 only transitory in plants, the shell corresponding to the 

 husks of a seed, the gills to the cotyledons, the foot to 

 the radicle, the fibres of the byssus to the spongioles. 

 And what may be said of the common coral and 

 encrinite save this that these and kindred creatures 

 are almost as much plants as animals, that the 

 name of zoophytes is rightly applied to them, and 

 that plants are excluded from the order radiata on no 

 just pretext ? Indeed, only one conclusion may be 

 drawn from the fact which is too familiar to need 

 illustration by instances that plants and animals in so 

 many ways exhibit the same radiate and ramified and 

 helical modes of growth. 



