Biogenesis of Nicotine

768 NATURE recipient, nulliparous, has missed three menses and the Aschheim-Zondek test is positive. The personal histories of the three recipients indicate a high degree of integrity and the source of the conceptions is valid. The ability of glycerol-treated, frozen and thawed human spermatozoon to fertilize and actuate the human ovum has been observed. General 'clinical application of this fact must wait until normal embryonic development has been observed and the progeny are declared normal. We wish to thank Drs. W. C. Keettel and J. T. Bradbury, of the Department of Obstetrics and Gynecology, for their co-operation and encouragement. R. G. BUNGE J. K. SHERMAN Department of Urology, Medical School, State University of Iowa, Iowa City, Iowa. Aug. 19. 3fontegazza, P., Rend. reale Instit. Lomb., 3, 183 (1866). 'Jahnel, F., Klin. Wschr., 17, 1273 (1938). Shettles, L. B., Ame,·. J. Physiol., 128, 408 (1940). Hoagland, H., and Pincus, G., J. Gen. Physiol., 25, 337 (1942). 'Polge, C., Smith, A. V., and Parkes, A. S., Nature, 164, 666 (1949). 'Sherman, J., and Bunge, R., Proc. Soc. Ezy. Biol. and Med., 82, 686 (1953). 'Parkes, A. S., Brit. Med. J., ii, 212 (1945). 1 Thoracic Glands of lphita limbata Stal. THE thoracic gland has been shown in a number of inseets to be the immediate source of the moulting hormone. It has been demonstrated recently that the neurosecretory cells of the brain activate the thoracic gland and thus bring about moulting. The thoracic glands in a number of insect groups still await discovery. Scharrer 1 suggests that the 'tracheal organs' in Nepa probably represent the thoracic glands ; \Villiams• cites the presence of thoracic glands in Oncopeltis. Wigglesworth• describes in detail the thoracic gland in Rhodnius, which is the only complete account of the glands in the Hemiptera ; he also points out that the 'tracheal organs' in Nepa reach their full development in the adult, while separate thoracic glands are present in nymphal instars which disappear in the adult. Prof. Wigglesworth (in litt.) informs me that a comparative study of thoracic glands in Hemiptera is being done in his Department by Mr. M. J. Wells. In Iphita limbata Stal. (Pyrhoeoridie: Hemiptera) the thoracic glands have been found in the last two nymphal instars as well-defined structures, associated with the inner lobe of the thoracic fat body. The gland on each side consists of a loose collection of large cells with conspicuous chromatin and secretion product, lying along the periphery of the inner lobe of the fat body, which is well tracheated. Under the ordinary microscope they are not visible unless stained, but they could easily be seen and studied under the phase-contrast microscope. Fig. 1 shows the cells of the gland under the phase-contrast microscope. These cells remain more or less in contact and show an irregular shape and lobed nuclei. They appear yellowish under the phasecontrast optical system. October 24, 1953 voL. 1n Fig. 1 The study of the structure and physiology of these cells is being continued. K. K. NAYAR Zoology Laboratories, University College, Trivandrum. S. India. ,Tuly 3. • Scharrer, B., Biol. Bull., 95, 186 (19!8). 'Williams, C. M., Biol. Bull., 97, 111 (19!9). 'Wigglesworth, V. B., J. Exp. Biol., 29, 561 (1952). Biogenesis of Nicotine FOLLOWING the demonstration that the aminoacid tryptophane can readily be converted by barley plants into the alkaloid gramine1, the study of the biogenesis of alkaloids carried on here has included investigations into the possibility that nicotine may arise from tryptophane in a manner similar to the formation of nicotinic acid in animals and microorganisms•. Recent discussions of this possibility 3 • 4 prompt me to describe part of these investigations. DL-Tryptophan, containing carbon-14 in the ~-position, was fed, in the form of its acetate, to young tobacco plants via the roots. The leaves, which became radioactive, were dried, digested with 40 per cent sodium hydroxide solution, steam-distilled and the volatile bases isolated as hydrochlorides. By chromatography on Whatman No. 1 paper using n-butanol/hydrochloric acid• as a solvent and developing upwards, the nicotine from the plant was separated from other products, its position (Rp 0·2 at 20°) being located by the bismuth nitrate/potassium iodide reagent•. The nicotine spots so obtained were found to exhibit no radioactivity measurable by a thin-window counter. The results so far obtained lend no support to the theory that the tryptophane molecule in toto is converted into nicotine, although the possibility that the pyridine ring is formed from the indole moiety is not excluded. Further investigations into the problem are in progress. K. BOWDEN Department of Organic Chemistry, University, Leeds 2. Aug. 31. 'Bowden, K., and Marion, L., Can. J. Chem., 29, 1037 (1951). 'Dalgliesh, C. E., Quart. Rev. Chem. Soc., 5, 227 (1951). 'Mortimer, P. I., Nature, 172, 74 (1953). 'Itobinson, R., Nature, 172, 344 (1953). 'Munier, R., and Machboeuf, M., Bull. Soc. Chim. Biol., 33,846 (1951). © 1953 Nature Publishing Group  (...truncated)