𝔖 Bobbio Scriptorium
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Variables Related to the Understanding of a Science Unit as Presented by Computer Assisted Instruction

✍ Scribed by Wilfred E. Boykin

Book ID
114974716
Publisher
School Science and Mathematics Association
Year
1972
Tongue
English
Weight
281 KB
Volume
72
Category
Article
ISSN
0036-6803

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Acute and Chronic Toxicity of Veratrum V
Acute and Chronic Toxicity of Veratrum Viride††The Veratrum viride studied was the whole-powdered drug marketed by Irwin, Neisler & Co. under the name, Vertavis. The work reported herein was supported by a grant from this firm. The batch of powder used in these experiments was stated by the manufacturer to have been assayed biologically by the Craw method on Daphnia magna. One Craw unit of the material studied was stated to be 15.6mg. With regard to this assay, Mr. R. O. Craw has been so kind as to allow us to publish a brief explanation: A reference lot of Yerolrum oirid; powder was set-aside as a standard and a 10% w/v aqueous extract was made of this powder. The average median length of life in 50 assays of 1000 daphnia on immersion in the solution was determined to be 2.22 hours. The daphnia were considered dead when the heart was found to be in systolic standstill on microscopic examination. Succeeding lots of powder were assayed and their potency determined by relating the median length of life of daphnia to 2.22 hours, which is one unit. Twenty assays of 10 animals each were used on each lot of powder.‡‡The authors wish to thank Dr. J. F. A.,McManus of the Department of Pathology for a pathologic report on the tissues, and Mr. James Thomas and Mrs. Bobby E. Teague for technical assistance.
✍ Perdue, Adoline S. ;Bell, Frances ;Starnes, W.R. ;Hitchcock, Philip ;Teague, R.S 📂 Article 📅 1950 🏛 Elsevier ⚖ 346 KB 👁 2 views