106 ANIMAL PHYSIOLOGY.. [LESSON 31. 



panded tentacles are seen at a ; at the base of them (6) is the 

 mouth ; the stomach, provided with eight vertical partitions (d), oc- 

 cupies the centre of the animal. At the bottom of the stomach is 

 an outlet (e) for the transmission of the nutrient matter to a canal, 

 which communicates in like manner with the stomachs of all the 

 polypes, by which means the nourishment is made available for the 

 purposes of the commonwealth. Appended to the lower portion of 

 the stomach are the ovigerous (egg-producing) tubuli (/). 



LESSON XXXI. 



ACALEPHA. 



522. The surface of the Ocean, during the summer months, pre- 

 sents a vast assemblage of soft-bodied, gelatinous forms, of every size, 

 from many feet diameter, down to an inconsiderable speck ; all of them 

 as transparent as glass, all luminous at night, and many of them 

 sharply stinging the hand that touches them : from this latter pro- 

 perty they obtain their name ; the Greek word signifying a nettle. 



523. The best account of these animals is that given by Peron 

 and Leseueur, two French naturalists. 



" The substance of a Medusa is wholly resolved by a kind of in- 

 stantaneous fusion into a fluid analogous to sea water ; and yet the 

 most important functions of life are effected in bodies that seem to 

 be nothing more than, as it were, coagulated water. The multipli- 

 cation of these animals is prodigious ; and we know nothing certain 

 respecting their mode of generation. 



" They may acquire dimensions of many feet diameter, and weigh 

 occasionally from fifty to sixty pounds ; and their system of nutrition 

 escapes us. They execute the most rapid and continuous motions ; 

 and the details of their muscular system are unknown. Their secre- 

 tions seem to be abundant ; but we perceive nothing satisfactory as 

 to their origin. They have a kind of very active respiration ; its 

 real seat is a mystery. 



" They seem extremely feeble, but fishes of large size are daily 

 their prey. One would imagine their stomachs incapable of action 

 on these latter animals ; in a few moments they are digested. 

 A great number of these Medusae are phosphorescent, and glare 

 amidst the gloom of night like globes of fire ; yet the nature, the 

 principle, and the agents of this wonderful property remain to be dis- 



