PLASTICS 



275 



PLASTIDS 



microscop3'^ (Newman, S. B., Borysko, 

 E. B., and Swerdlow, M., U. S. National 

 Bur. Standards, J. of Res., 1949, 43, 

 183-199) uses n -butyl methacrylate for 

 mounting specimens which can be 

 sectioned for studj' under a microscope. 



Plastics in the form of sheets find 

 interesting uses. Microscopy with 

 plastic substitutes for cover glasses is 

 discussed by Richards, O. W., Small, 

 J. H. and Collyer, P. W., Stain Tech., 

 1944, 19, 59-62. Natural color plant 

 specimens have been mounted between 

 plastic plates by Fessenden (G. R., 

 loc. cit. under Acrylics 3). Preserved 

 flowers can be placed in transparent 

 plastic containers with a desiccant and 

 kept for long periods of time (Specht, 

 R. C, Engineering Progress, Univ. 

 Florida, 1950 IV No. 12, Gainesville). 



Polyester resins: Gross anatomical 

 and embryological specimens have 

 been mounted and are described in the 

 following articles: 



1. "Embedding Gross Sections in 

 Ward's Bio-plastic", T. H. Ro- 

 maniak. Ward's Nat. Sci. Bull., 

 1948, 22, 34. 



2. "The Mounting of Human Sections 

 in Bio-plastic," Ward's Nat. Sci. 

 Bull., 1950, 24, 27. 



3. "On the Mounting of Anatomical 

 Museum Specimens in Transparent 

 Plastic", Kampmeier, O. T. and 

 Haviland, R. N., Anat. Record, 1948, 

 100, 201-231 (Used Castolite on 100 

 specimens) . 



4. "The Relationships of Herniated 

 Intervertebral Discs to the Spinal 

 Cord and Spinal Nerves", (Used 

 Castolite). A. F. Reed and H. D 

 Kirgis, Abstract D2, Anat. Rec, 

 1951, 109, 146. 



5. "The Blood Vessels of the Jejunum 

 and Ileum in Man and Certain Lab- 

 oratory Animals", (Used Polysty- 

 rene). Abstract D 16, Anat. Rec, 

 1951, 109, 144. 



6. Charles H. Glines (with Alexander 

 Barry and Bradley M. Patten at the 

 Anatomy Dept., School of Medicine, 

 University of Michigan, Ann Arbor) 

 has prepared both cleared and 

 opaque embryos following techniques 

 set out in Ward's, "How to Embed 

 in Bio-Plastic". Glines and his 

 co-workers have devised some modi- 

 fications over methods described by 

 Kampmeier. These data are avail- 

 able in mimeograph form, and were 

 also presented at the 1951 meeting 

 of the Am. Assoc, of Anatomists 

 (Barry, A., Patten, B. M. and Glines, 

 C. H., Abstract D 31, Anat. Rec, 1951, 

 109,133). 



Demonstration sets composed of 



animal types have been prepared in 

 plastic for class use (Lucas, M. S. 

 report in preparation) in connection 

 with a study of "unknown" specimens 

 (Study 1, 1951, Guide for Laboratory 

 Studies Biological Science, Mich. State 

 College Press, E. Lansing). Each 

 animal is prepared individually in a 

 block and later is set with others into 

 an illuminated box or into a large block 

 of plastic. This provides an attrac- 

 tive variety of unknown animal types 

 to supplement conventional identifica- 

 tion studies. Plastic-corrosion speci- 

 mens prepared by injecting blood ves- 

 sels of animals with Vinyl Acetate 

 (Vinylite) can be embedded in blocks 

 of polyester resins (Service Bulletin 

 No. 5, 1950, and Natural Science Bul- 

 letin 1950, 24, 3, Ward's Natural Science 

 Est.). Vinylite of the type carried by 

 this firm contains a pigment which will 

 not bleed out of the preparation into 

 the plastic block, whereas, latex-in- 

 jected vessels will permit dye diffusion. 

 The use of plastic in reconstructions 

 from serial sections is advocated by 

 Boyer, C. C, Anat. Rec, 1948, 100, 

 191-197. 



In soils studies, vinvlite resin (The 

 Bakelite Corp., 230 N. Mich. Ave., 

 Chicago 1, 111.) and cellulose acetate 

 (Hercules Powder Co., Cellulose Prod- 

 ucts Dept., Parlin, N. Y.) are used to 

 make soil profiles (Berger, K. C. and 

 R. J. Muckenhirn, Soil Sci. Soc of 

 Amer. Proc, 1945, 10, 368-370; Smith, 

 H. W. and C. D. Moodie, Soil Science, 

 1947, 64, 61-69). Permanent plastic 

 color standards for rapid soil and plant 

 tissue testing are emploved bj^ Lynd, 

 J. Q., and L. M. Turk, J. Soc. Agron- 

 omy, 1948, 40, 940-941. Plant ma- 

 terials showing deficiency symptoms 

 can be prepared in plastics as described 

 by Lynd, J. Q., Quart. Bull. Mich. State 

 Coll. Agric. Exper. Station, In press. 

 Art. No. 1238. 



A process for embedding flowers in 

 plastic so as to preserve their natural 

 shape and color has been described by 

 Specht, R. C, Engineering Progress 

 at the U. of Fla., 1950, IV No. 12, 

 Gainesville, $1. 

 Plastids are by definition simply formed 

 bodies. The term is usually ap])lied to 

 certain cytoplasmic bodies in plants. 

 They may be colorless leucoi)l.astids, 

 chloroplastids containing chlorophyll 

 or chrornoplastids containing other pig- 

 ments. Chlorophyll thus segregated 

 in these bodies acted on by light plays 

 its part in starch production, as hemo- 

 globin (erythroplastids) acts in trans- 

 port of oxygen. The chloroplastids are 

 easily visible microscopically. Special 



