. Contributions from the Botanical Laboratory, vol. 11. Botany; Botany. r CYTOLOGICAL FIXATION WITH THE LOWER FATTY ACIDS THEIR COMPOUNDS AND DERIVATIVES^ By Conway Zirkle (Department of Botany, University of Pennsylvania) With Plates I—IV Received for publication. May 12, 1932 In spite of the fact that acetic acid has long been recognized as one of the most destructive of cytological reagents, it is at present an essential component of practically all fixing fluids in common use. It forms a part of such mixtures as Allen's, Bouin's, Carnoy's, Plemming's, Gilson's and Nawaschin's, to cite only
. Contributions from the Botanical Laboratory, vol. 11. Botany; Botany. r CYTOLOGICAL FIXATION WITH THE LOWER FATTY ACIDS THEIR COMPOUNDS AND DERIVATIVES^ By Conway Zirkle (Department of Botany, University of Pennsylvania) With Plates I—IV Received for publication. May 12, 1932 In spite of the fact that acetic acid has long been recognized as one of the most destructive of cytological reagents, it is at present an essential component of practically all fixing fluids in common use. It forms a part of such mixtures as Allen's, Bouin's, Carnoy's, Plemming's, Gilson's and Nawaschin's, to cite only the better known, and it is the only chemical these fixatives have in common. Recent investigations of chromosome structure, of the finer details of the resting nucleus, etc., have been carried on with the aid of acetic acid fixation. Such fixation, however, destroys cytoplasmic detail (Lee 15). Mitochondria and young plastids are dissolved and vacuoles distorted. Bensley (2) reported that cytoplasm in meristomatic cells, fixed with Flemming's, Hermann's, Zenker's and Carnoy's, contain artificial spherical vacuoles, while such fluids as that of Kopsch, which contain no acetic acid, preserve the true canalicular vacuoles of Holmgren. MoTTiER (21), by reducing the acetic acid in Flemming's strong solution to 15 % of its usual concentration, was able to investigate mitochondria and the primordia of plastids. He even secured clear images when he eliminated the acid completely. The question arises: what is the property of acetic acid which makes it valuable as a constituent of fixing fluids ? The generally accepted answer is as follows: most cytological preservatives, chromic acid, formal- dehyde, etc., cause tissue to shrink while acetic acid makes the tissue ' -^ i — A *^ -»^' J» <! - I ^ ». j « C \ . » hr-"- 1 This investigation was started at the Bussey Institute, Harvard University. Cytological fixation with the lower fatty acids their compounds and deri
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