520 GENERAL BIOLOGY 



Concerning laboratory drawings. 

 Draw the thing as you see it, but first be sure: 



1. That you see the right thing; don't draw dirt or air 

 bubbles. 



2. That you see it in normal condition; look your 

 material over, and make sure what is normal; and then 

 don't draw distortions or freaks. 



3. That you see the significant things; and then don't 

 draw endless repetitions, such as whole sections of similar 

 cells — but represent those things that mean something to 

 you. 



4. Don't draw what you can't see. 



5. Draw with as few lines as possible (smearing with a 

 pencil is not drawing) ; shading is usually unnecessary. 



6. In starting a drawing, look to proportions; usually 

 there are a few main structural lines discoverable, and if 

 these are first laid down with a little care, a well propor- 

 tioned drawing is easily built upon them. 



7. Use mechanical means, especially for diagrams, when 

 the subject admits of it; forms, or a compass for m_aking 

 circles, and a ruler for parallel lines, etc. 



2. Materials for practical studies. 



A few suggestions are here made as to useful ways of 

 handling the materials that are less familiar to the experience 

 of the average laboratory student at the present time. 



On collecting and concentrating aquatic organisms. A 

 very simple and inexpensive outfit will procure these organ- 

 isms in very great variety and abundance, and with little 

 expenditure of time. 



I. A cone-shaped dip net, some four inches in diameter, 

 on a long light handle. The cone may be made of fine swiss, 

 of China silk, or, better of no. 12 silk bolting cloth. Swept 

 through the water the plankton is swept into the point of the 



