2114 Journal of Applied Microscopy 



more common instances of the alternation of stages in the rust fungi, as for 

 examples, the cases just mentioned of the wheat rust and apple leaf rust. Such 

 demonstrations are so clear and convincing that they should be employed in all 

 colleges and academies, without exception, in place of the too common word 

 explanations of lectures and text memorizing. The student is thereby forcibly 

 impressed with the truth of the actual existence of these alternations, whereas he 

 might always remain a little skeptical if his knowledge should go no farther than 

 the mere reading of the text describing former investigations. The writer knows 

 of teachers of science who until very recently did not believe in the actual exist- 

 ence of the alternation of stages in the rust fungi. Of course, they had never 

 seen an actual demonstration. Mark Alfred Carleton. 



U. S. Department of Agriculture. 



A Simple Method of Making Wall Charts. 



The descriptions of biological wall charts by Orson Howard of the Univer- 

 sity of Utah, and F. D. Heald of Parsons College, Iowa, published in the Jour- 

 nal OF Applied Microscopy, interested me greatly. 



Neither of the methods detailed, however, seem to me equal in simplicity to 

 that followed in work for the Histological and Embryological Laboratories of 

 the Woman's Medical College of Pennsylvania. 



At the suggestion of Dr. H. H. Cushing, director of the laboratories, under 

 whose supervision the charts were made, I purchased a quantity of the best 

 glazed, white window-curtaining, which was cut into two-yard lengths. The 

 pieces were hemmed at either end, into the lower hem being slipped a cylindri- 

 cal wooden roller, and into the upper a flat Curtain stick, to give the stiffness 

 necessary for convenience in hanging. 



The drawing was done with paraffin pencils of the sort usually seen in black 

 for marking freight and express packages. Investigation proved that these pen- 

 cils were manufactured in all colors by the Acme Pencil Co., Chester, Pennsyl- 

 vania, and I was able to select shades reproducing very satisfactorily many of 

 the stains, viz., carmine, haematoxylin, eosin, picric acid, methylen blue-black, 

 etc., used in mounting microscopic specimens. 



The pencils cost but fifty cents a dozen, are economical in use, and the paraf- 

 fin does not rub. 



A faint line can be readily erased with a knife, and I found it convenient to 

 make such a faint plan and sketch of each drawing, and when satisfied of its 

 correctness, to go over the lines heavily, filling in and shading as required. 



The pencils are exceedingly easy to use, and although the very fine drawing 

 which is done with pen and ink cannot be rivalled by this method, the work is 

 quite as fine as can be readily seen across a class-room. 



In this way some one hundred and eighty very effective charts were made 

 at very little expense, from plates and illustrations selected by Dr. Cushing from 

 fifteen or twenty different text-books on histology, anatomy and embryology, and 

 the students are thus enabled to have the benefit of well illustrated lectures. 



