PRESERVATION OF SPECIMENS IN PLASTICS 



31 



suitable for casting and embedding purposes are also described in the 

 literature on plastics (1). 



In the investigations carried out in the United States Department of 

 Agriculture in this field it was found that methyl and ethyl methacryl- 

 ates, because of their exceptional clarity and stability in light, were 

 particularly suitable for embedment purposes, and they were accord- 

 ingly adopted as the basis for the embedding method developed in the 

 Department's research program. Development of this method for 



fc^_ 



Plate 2. — Biological specimens preserved in three-dimensional form in plastic blocks, 

 a, Seed capsule of Datura stramonium; b, strawflower; c, katydid; d, minnow; e, 

 closed smut on oats; /, yellow and purple pansy; g, grasshopper; h, mosquito larvae 

 and adults; i, blue bachelor's button; j, wood tick engorged with blood; k, small 

 crab; I, dragon flies; m, Penicillium mold; n, Rocky Mountain wood ticks; o, ergot 

 sclerotia from grain; p, tussock-moth caterpillar; q, Japanese beetles; r, garden spider; 

 s, box-elder bug; t, pink rose petals; u, screw bean from "tornillo" tree (Prosopis 

 pubescens)- Specimens were prepared by author using procedures described. 



