6 LESSON I. 



stance. Animals as well as vegetables, are 

 supplied with a greater number of glands ; the 

 tears of animals are an example of secretion 

 formed by means of such organs, so is the honey 

 of plants. As the glands form little reservoirs, 

 they often appear like small swellings, percep- 

 tible to the sight and touch. Now can you tell 

 me what glands are ? 



Child. They are organs by which are secre- 

 ted some particular fluid from the general fluid 

 of the body. 



Teacher. To return to the mantle ; it some- 

 times envelops the mollusk like a purse, leaving 

 an opening only where its mouth is situated ; 

 sometimes it extends on the two sides, forming 

 expansions which perform the part of fins. 

 Sometimes it spreads over the shell itself, which 

 in this case has always a fine polish. Compare, 

 as I desired you, the mollusk s, with other 

 animals, and tell me what further peculiarity 

 you discover in them. 



Child. They have no bones, their bodies are 

 only a mass of soft flesh. 



Teacher. They have certainly no bones ; but 

 in the mollusks which we purpose studying, 

 the shell, by acting as a support to the body, 

 seems in some measure to answer the purpose of 

 bones. What more do any of you discover 

 in these animals ? 



Child. They do not appear to have any blood . 



Teacher. They have not red blood as we 

 have ; but are they composed entirely of solid 

 matter ? 



