110 



EECEEATIVE SCIENCE. 



for Mr. Bowerbank to close an open ques- 

 tion. He discovered that the sponges are 

 provided with cilia, and thus fairly esta- 

 blished them in the animal kingdom. He 

 saw not only evidences of cilia, but the true 

 hair-like processes playing with the regularity 

 of paddle-wheels, transmitting a stream of 

 water through the mass of the tough skeleton, 

 and by a regular process of fishing obtaining 

 its share of the bounties of the sea. Here is 

 a fine boulder, half covered at this present 

 low tide. With my bare arm I can reach 

 down into one of its rough hollows, and with 

 detective fingers obtain to a certainty one of 

 the best of the sponges for microscopic ob- 

 servation. Here it is; a dirty-looking, funnel- 

 shaped mass, and its name a very inviting one, 

 "Crumb of bread," which it certainly some- 

 what resembles. Transferred to a small jar of 

 fresh sea-water, wrapped round with a strip 

 of wet flannel, and at once conveyed to the 

 basket, it will be alive when we get home, 

 and perhaps may live a week ; and if we put 

 on all the power we have, with a good light, 

 we shall see the cilia imitating clock-work. 

 In the fresh-water sponges [Sjpon^illa), simi- 

 lar ciliatory appendages have been observed, 

 and were admirably studied by Lieberkiihn, 

 who noticed that they disappeared with the 

 approach of winter, indicating that probably 

 at that season the creature ceases to feed, 

 and becomes partially or perhaps whoUy 

 dormant. 



Another good sponge, which we may ob- 

 tain almost anywhere on the coast, is the 

 " Sack," which is not so suitable to show the 

 cilia, but the best of all to illustrate the rela- 

 tion of the sponges to the history of flint. 

 Tear it up, and put a fragment under the 

 microscope, and, wonder of wonders ! see the 

 maze of geometric forms exhibited in the 

 bones of the creature ; for who can help re- 

 garding the spicules as bones, even though a 

 sponge be invertebrate P It is a wUderness 

 of sUiceous needles ; no, not needles, pins, 

 for every one has a knob at the base, and 



they cross and recross, so that the eye is 

 bewildered to trace them out finally ; and 

 yet all is order and unity. The fingers of the 

 Almighty Maker were not more troubled in 

 fashioning that microscopic lace of flint than 

 in piling up the pinnacles of the Andes. 

 The jelly-like body of the creature permeates 

 these spiny meshes of lime and flint, and 

 thus, from the support it derives from them, 

 they may truly be regarded as the bones of 

 a boneless creation. Death dissolves the 

 living film, but the spicules remain unhurt 

 for a thousand years, and reveal themselves 

 in their original sharpness and geometric 

 accuracy of pattern to the eye of that pene- 

 trator of mysteries, the microscope (2, 3, 5). 

 The simplest of the Protozoa is the Hhizo- 

 poda, of which we have an easily procured 

 type in the Amoeba, a semi-transparent orga- 

 nization, found in ponds and infusions. They 

 are examples of polygastric animalcules, de- 

 scribed by Pritchard as " with one aperture 

 only to the body, and no alimentary canal or 

 lorica." A specimen of Amceha radiosa is 

 represented in the cut at 1. It consists of a 

 jeUy-like body, capable of expansion in such 

 a way as to manufacture for itself legs and 

 arms, for it has no appendages whatever but 

 such as it produces at will. Thrusting out 

 portions of its body, it forms what are called 

 " pseudopodia," of which the specimen repre- 

 sented has four. If we were to watch it one 

 or two might be withdrawn, or one or two 

 more extemporized, according to its own ec- 

 centric vagaries. By means of these pseudo- 

 podia it moves from place to place, and also, 

 by a process of grasping and contracting 

 them, it tucks into its body any morsel with 

 which it comes into contact, and thus makes 

 its temporary legs serve as feelers, feeders, 

 and organs of locomotion. Strictly speaking, 

 it has no mouth, and will as readily wrap up 

 a grain of sand as a wandering infusorium ; 

 but a power of digestion it has, and ihe sand, 

 or the rejected portions of the embraced 

 infusoria, are expelled through some part 



