Laboratory Work. 3 



long and short diameters, using the short diameter, for 

 instance, as a measuring rod ; and then with a very light 

 touch of the pencil, making a barely visible line, draw the 

 outline. If the form is not right at the first attempt, correct 

 it before rubbing out the false line, for the latter may serve 

 as a guide in correcting the error. When the form has 

 been satisfactorily drawn, rub out the false lines once for 

 all, and retrace the final outline with a firm touch so that 

 it stands out sharply, but the pressure of the pencil must 

 not be hard enough to dig into the paper. 



Colored pencils are very helpful for giving distinct tints 

 to the different parts of a drawing, but they should be used 

 only where a definite purpose is to be served, as in calling 

 attention to homologous parts in different drawings. The 

 coloring should be done with very light cross-hatching 

 strokes until an even light tint is produced. If satisfactory 

 results are not obtained in this way, the color can be dis- 

 tributed more evenly by rubbing over the colored areas 

 with a paper or chamois stump used by artists in crayon 

 shading. 



3. The Student at Work. — The student should think of 

 his work as he proceeds. The drawings and notes are in- 

 tended to assist him in gaining a clear conception of the 

 problems before him, and they are good evidence of his 

 success or failure ; but he should possess his subject more 

 completely than the drawings and notes may show. The 

 laboratory is so much limited space in which certain con- 

 veniences for work are provided. Were it not for these 

 conveniences, it would be better to study the subjects out 

 of doors in their natural surroundings. The student who 

 thinks as he works associates the subject with the natural 

 conditions, and sees the bearing of what he is learning in 

 the laboratory on the fife of plants as they occur in nature. 



