THE AMERICAN BOTANIST. 37 



both cotyledons, removing the endosperm, etc., and comparing 

 the growth of such mutilated plants with normal ones. These 

 experiments, however, need to run for several days and are 

 not calculated to hold the interest of high school pupils. With 

 such students it may be taken for granted that they understand 

 that the stored starch, oil and proteid serve the seed exactly 

 as they would an animal. 



The pupil will readily understand that some of the food 

 is used by the seedling in forming new parts, but the idea that 

 the food is a source of energy for the plant is more obscure 

 since at first glance the seedling does not seem to use energy. 

 The force used in pushing through the soil should be con- 

 clusive on this point. It is often assumed that the bursting of 

 the testa is an illustration of the use of energy, and this force 

 is usually shown by the time-honored experiment of filling a 

 botttle with germinating seeds which in swelling will burst 

 the bottle. This experiment, however, is probably more phy- 

 sical than physiological. A bottle full of small cubes of dry 

 wood might be expected to give the same result. A more 

 appreciable idea of the force exerted by growing plants may 

 be had by placing a pane of glass over a pot of thrifty young 

 seedlings. By placing varying weights on the glass it will be 

 easy to see just how much force a given number of seedlings 

 can exert. Heat is another form of energy liberated by plants, 

 but in such small quantities that it is difficult to detect. By 

 taking two thermometers that read alike and plunging one 

 in a jar of germinating seeds while the other is placed in 

 a similar jar of dry seeds it is possible to detect the heat given 

 off but it frequently happens that the presence of bacteria in 

 the germinating seeds gives a temperature that while pleasing 

 to the experimentor is much too high to be accurate. 



Some of the experiments with seeds that are often per- 

 formed in the high-school course but which do not seem to be 

 essential are those designated to discover where the caulicle 



