assimilated by the protoplasm in the making of new living matter, or perhaps without the first process of synthetic assimilation some of the inorganic salts, nitrates, and carbohydrates meeting in the protoplasm are assimilated into new living matter directly. FOOTNOTES: [15] In lieu of Arisæma make a practical study of the pea. See paragraph 216_a_. [16] Dissolve a half gram of osmic acid in 50 _cc._ of water and keep tightly corked when not using. CHAPTER XI. RESPIRATION. =220.= One of the life processes in plants which is extremely interesting, and which is exactly the same as one of the life processes of animals, is easily demonstrated in several ways. =221. Simple experiment to demonstrate the evolution of CO₂ during germination.=—Where there are a number of students and a number of large cylinders are not at hand, take bottles of a pint capacity and place in the bottom some peas soaked for 12 to 24 hours. Cover with a glass plate which has been smeared with vaseline to make a tight joint with the mouth of the bottle. Set aside in a warm place for 24 hours. Then slide the glass plate a little to one side and quickly pour in a little baryta water so that it will run down on the inside of the bottle. Cover the bottle again. Note the precipitate of barium carbonate which demonstrates the presence of CO₂ in the bottle. Lower a lighted taper. It is extinguished because of the great quantity of CO₂. If flower buds are accessible, place a small handful in each of several jars and treat the same as in the case of the peas. Young growing mushrooms are excellent also for this experiment, and serve to show that respiration takes place in the fungi. [Illustration: Fig. 101. Test for presence of carbon dioxide in vessel with germinating peas. (Sachs.)] [Illustration: Fig. 102. Apparatus to show respiration of germinating wheat.] =222.= If we now take some of the baryta water and blow our “breath” upon it the same film will be formed. The carbon dioxide which we exhale is absorbed by the baryta water, and forms barium carbonate, just as in the case of the peas. In the case of animals the process by which oxygen is taken into the body and carbon dioxide is given off is _respiration_. The process in plants which we are now studying is the same, and also is respiration. The oxygen in the vessel was partly used up in the process, and carbon dioxide was given off. (It will be seen that this process is exactly the opposite of that which takes place in carbon dioxide assimilation.)