and Laboratory Methods. 1643 



acute vision than the other. Make the drawings of small objects of the right 

 proportion, and the actual size magnified. The larger ones may have to be 

 reduced to bring them onto the paper. If the object has a definite relation to 

 environment do not draw it upside down. It must also be remembered that 

 motions are magnified as well as the objects themselves. 



Absolute regard for the truth is the first requirement in scientific drawings 

 and descriptions, and the qualities required for good work are accuracy, cleanli- 

 ness, patience, skill, persistency, good judgment, and logical ways of thinking. 

 The drawings should be exact in all details ; the sketches may be more or less 

 diagrammatic. The notes should be written in the best English at the command 

 of the student. The facts should be stated in concise but complete declarative 

 sentences, without rhetorical ornamentation. The observations must always be 

 recorded at the time when they are taken. One's memory should not be trusted 

 in recording scientific facts. 



Finally, it must be remembered that one of the first things to be accom- 

 plished is to educate the hand for delicate manipulations. And it is also well to 

 keep in mind that scalpels and razors are not intended for sharpening lead pen- 

 cils or cutting the table, that oculars and objectives are never to be dropped, 

 that stoppers should not be laid down on the bare table, that books and note- 

 books are not to be soiled by the wet and dirty fingers, that bottles and tumblers 

 of water are not to be overturned, and that one should understand the objects 

 studied before attempting to draw or describe them. 



OUTLINES. 



Preliminary study of the living cell, to show the general cell structure and 

 the activity of protoplasm. 



I; Philotria canadensis (Mx.) Britt. " Elodea," Waterweed. 



This is a very common plant growing submerged in ponds, creeks, etc. It 

 will grow well for a long time if simply pulled up and placed in a covered glass 

 jar. 



1. Carefully pull off a few young leaves and mount in water. Sketch the 

 entire leaf under low power. Make the drawing about five inches long. Describe 

 the shape, margin, color, midrib. Are there any other veins ? 



2. The leaf is composed of cells. How many across the leaf ? How many 

 lengthwise ? Is the leaf more than one cell in thickness ? About how many 

 cells on the upper surface ? 



3. Cut cross sections with the razor by holding some leaves between elder 

 pith. How many cells in thickness, on the average ? 



4. Suppose the leaf averages three cells in thickness, about how many cells 

 in the entire leaf ? 



5. Under high power, draw several adjoining cells, carefully showing details. 

 (Draw the walls as represented in Fig. 1.) What is the general shape of the cells ? 

 The contents of a cell are protoplasm and sap or water. There is usually some 

 dead food material present. 



6. Notice that the protoplasm is made up of cytoplasm, nucleus, and chloro- 



