120 SECRETION IN THE INFERIOR ANIMALS. 



peculiar substance, called picromel, or the resin of the 

 bile. 



Emily. Does this function in the inferior animals 

 vary as much as respiration, circulation, &c. ? I hope 

 you will not confine your view of it to man alone, for to 

 me the history of the vital functions as they exist in the 

 inferior animals, is no less interesting. 



Dr. B. The function is probably performed in the 

 same way in them that it is in man ; its products how- 

 ever are varied almost to infinity. As it would be for- 

 eign to our purpose to take them up in detail, we must 

 be content with looking only at a few of the most impor- 

 tant and curious. A singular product of secretion in the 

 mammiferous class, are the horns of the ruminating ani- 

 mals. In the winter or spring season, an unusual quan- 

 tity of blood is determined to the head, a membrane is 

 formed on the skull containing numerous vessels, bony 

 matter is secreted from them, and the membrane extends 

 until the whole horn is produced. In some families this 

 process is performed annually the horns being shed 

 once a year. 



The venom of serpents is also a product of secretion. 

 The venomous serpents are provided with a couple of 

 long fangs, which they have the power of erecting and 

 depressing at will. At the bottom of the fang is a little 

 gland that secretes the poison, and a canal in the middle 

 of the fang gives issue to the venom when required. 

 The shells of the shell-fishes those beautiful shells 

 whose brilliant and variegated colors you have so often 

 admired, are secreted from the membrane that forms 

 the envelope of the animal. What is still more strange, 

 those branches of coral, sea-fans which you have fre- 

 quently seen, are secreted by animals of microscopical 

 dimensions. 



Emily. Indeed. Dr. B., I have been told that the 

 coral itself is of an animal nature, and have been rallied 

 not a little for expressing my incredulity about the fact, 

 for it always appeared to be nothing but limestone. 



