LOWEK AND HIGHER EORMS. 



FIG. 2. 



9 



A leaf of Duck- weed (a), much magnified, and fifteen microscopic organisms plants 



and auimala highly magnified. 



1. Vorticella convallaria. 



2. Volvox globator (a plant). 

 8. Vaginicola crys/.allina. 



4. Amphileptus fasciola. 



6. Navicula hippocampus (a plant). 



6. Amoeba diffluens. 



1. Trachelocerca olor. 



9. Stentor polymorphus. 



10. Bufsaria tntncatellct. 



11. Pandorina morum. 



12. Stylonichia mytilus. 



13. I'aramecium aurelia. 



14. Euplotes truncatus, 



15. E. sl.riatus. 



8. Polytoma uvella. 



ly complicated structure, and eacli of the many functions 

 performed by an appropriate set of organs. Such animals not 

 only have organs by which to secure food, but also a stomach 

 and other requisite organs to digest the food, and to change 

 it into blood ; vessels called arteries, capillaries, and veins, 

 in which the blood circulates in all parts of the body, and 

 thus nourishes every part ; a heart to propel the blood ; 

 lungs or gills, to perform the functions of respiration, by 

 which the blood is purified ; glands, to form the various 

 kinds of secretions ; organs of excretion, to rid the body 

 of waste material ; muscles, and a skeleton to move the 

 parts of the body, and by means of which locomotion is 

 effected ; organs for the purposes of reproduction ; a com- 



1* 



