354 THE MICROSCOPE. 



each part has devoured a worm as long as itself." Still 

 more wonderful is the fact, that if turned inside out, 

 the parts at once accommodate themselves to their new 

 condition, and carry on all their functions as before 

 the accident. Indeed, this animal seems so peculiarly 

 endowed with the germs of vitality in every part of its 

 body, that it may be cut into ten pieces, and everyone 

 will become a new, perfect, living animal. This seems 

 bordering on the vegetable kingdom, in which it is 

 common to propagate by means of slips from the mature 

 shrub. 



The best known of the British species are Hydra mil- 

 garis, Common polype, H. viridis, Green polype, H. Tusca, 

 Brown polype, H. verrucosa, and H. lutea. 



Every reflecting person who reads even the slight sketch 

 we have given of this polype tribe must be struck with 

 astonishment at a creature so primitive in structure, pos- 

 sessing the actions, sensations, and powers of higher 

 organised beings. The stomach is but one simple struc- 

 tureless membrane or cell, the external surface-cells form- 

 ing a kind of double skin, the inside a mere wall of cells 

 running crosswise, possessed of a velvet-like surface, and 

 red or brown coloured grains held together by a glutinous 

 substance. This singular formation, with some of the 

 functions of animal life, has led to many learned surmises 

 and discussions tending to the most important results in 

 the science of physiology. 



TUBULARIAD.E. The Tubular or Vaginated Polypes are 

 of an arborescent appearance ; the animals live near the 

 ends of branches, and are found attached to stones, sea- 

 weeds, and shells. 1 The Tubularia indivisa, " Individed 

 tubes," rise up like a tuft of herbage, of a horn colour, to the 

 height of twelve inches. Ellis says, " they seem part of 

 an oat-straw with the joints cut off." At the summit 

 protrudes the scarlet-coloured polypes, well furnished with 

 tentacula, and connected with a pinkish fluid that fills the 

 tubes. It was in these that Dr. Eoget discovered the 

 singular peculiarity of a circulation, similar to that seen 

 in many plants. He says, " In a specimen of the Tubu- 



(1) These are grouped with Hydroida, and at the head of the family stand 

 Van Beneden's Hydractinia ; and Gaertner's Coryne. 



