PTOLEMY. 523 PUBERTY. portance, and consist of descriptions of various kinds of projections (q.v.), the theory of the mu- sical scale, chronological and metaphysical treat- ises, and a summary of the "hypotheses employed in his great work, the Almayast. Others of Ptole- my's works have been lost, and it is still a moot point whether or not they contained a treatise on optics, as a Latin version of what is said to have been an Arabic translation of Ptolemy's original treatise on that subject is still in existence. The Almagest and the Geography were the standard text-books to succeeding ages, the first till the time of Copernicus, the second till the great maritime discoveries of the fifteenth cen- tury showed its deficiencies. They have passed through numerous editions, the best of which are, for the Almuqest and most of Ptolemy's minor works, that by Halma (Paris, 1813-l'(>-19-20) ; and for the Oeogruphij, the Latin versions of 1482 and 1490, published at Rome, the editio princeps of the Greek text bj' Erasmus ( Basel, 1533), and the Elzevir edition (Leyden, 1619). The catalogue of stars has been frequently re- printed separately, the last and best edition being that of Francis Baily, vol. xiii. of the Memoirs of the Iloi/al Astronomical Society (London, 1843). PTOMAINES, to'manz (from Gk. n-Tu/xa. pto- ma, corpse, from Triwreiv, piptein. to fall : connected ■with Tr^T«r8ac, petesthui, to fly, Lat. pctcre, to at- tack, seek, Skt. pat, to fly, fall). A name applied to a class of poisonous organic substances of ani- mal origin, extremely similar in their chemical and physical properties and physiological action to the vegetable alkaloids. The similarity of the ptomaines and the alkaloids is important inas- much as it throws doubt on the results of post- mortem analyses for the detection of vegetable poisons administered during life. Ptomaines are among the characteristic products of the putre- factive changes taking place in the body after death. It seems, however, that these poisons can- not be detected before tbe expiration of about two days after death. If therefore analysis should reveal the existence of poisonous matter before that time, the conclusion would be that it had been administered during life; but if the analyti- cal tests should be applied after the lapse of two days, the results would be subject to serious doubt. The effects that often follow from using bad fish or canned meat are prol)ably due to the action of ptomaines. There is also increasing evi- dence that the symptoms of many diseases are caused, not by the specific micro-organisms them- selves, but by the ptomaines produced by them. Chemically the ptomaines are amines; that is to say, they contain one or more XH, groups at- tached to hydrocarbon radicles. Following are a few of the more important ptomaines known: CH3 Iso-pkenyl-etliylamine, CJl-JCH . one of the products of the pancreatic putrefaction of gel- atin, was isolated by Nencki in 1870. Cadnrerine, penta - methylene - diamine, NH„ (CH.);H;, is found in corpses during the earlier stages of putrefactive decomposition : it is a liquid solidifying to a crystalline mass at low temperatures and forming crystalline compounds with acids and with certain salts. tutresceine. tetra - methylene - diamine. XH. Vol. XVI.— 34. (CHjjjNH,, is found in considerable quantities in putrid herrings and in corpses during the lat- ter stages of putrefactive decomposition; it is, like cadaverin, a liquid crystallizing in the cold and combining with acids and certain salts to form crystalline compounds. Choline, trimethyl-oxvethvl-ammonium hvdrox- ide, (CH3),X(0H)CH,CH,0H, is found among the products of decomposition of pig's or ox bile; it is a thick, colorless liquid readily de- composing if mi.ed with water and healed : it acts as a strong base, forming dcli(iueseent salts with acid, and also cr3stalline compounds with certain salts. It may be prepared from the yolk of eggs by decomposing the lecithin of the latter as follows: the jolk is carefully extracted with alcohol and ether, and the residue is boiled with caustic baryta; on precipitating the barium with carbonic acid and filtering, the solution is evapo- rated and the residue extracted with absolute alcohol, from which the choline is precipitated in the form of its platinum-chloride salt and the lat- ter is decomposed with sulphureted hydrogen. Wurtz succeeded in preparing choline syntheti- call}'. Neurine, trimethyl-vinvl-animonium-hvdroxide, (CH3),N(0H)CH=CH,,*is chemically similar to choline, from which it may be prepared; it is a highlj' poisonous liqiiid ptomaine, forming crystalline coni|)ounds with acids and with cer- tain salts; it is a common product of the putre- faction of meat. PTOSIS ( Neo-Lat., from Gk. -twctis, fall, from TT/V-ffv, piptein, to fall). A falling; a prolapse. Ptosis is the term commonly used of a falling of the eyelid. (See Eye, Diseases of). Enterop- tosis is a prolapse of the intestines into a lower plane than normal, owing to laxity of the ab- dominal walls. Gastroptosis is a falling of the stomach, which occurs in cases of retention of food in that organ, whei'eby it is weighted heavily, and also in cases in which the walls of the viscus are weak. PUBERTY (Lat. puherfas. from puher, pubes, mature) . The period of life at which the genera- tive organs of the male or female become capable of exercising the function of reproduction. The term is also applied to the changes in the special organs and the general .system that accompany the onset of this period. Sexual maturitv is reached earlier in warm climates. The age at which puberty is established in temperate zones is. in males, between sixteen and eighteen; in fe- males, between t'cuirteen and sixteen: but it can- not be reckoned by age alone, and is influenced by national or hereditary peculiarities and by some diseases. The changes noted in the male at ])uberty are a. development of the larynx with the "breaking' and deepening of tbe voice, a growth of hair al)OUt the face. ])ubes and other parts of the body; the fuller development of the sexual ap])aratus, with secretion of the seminal and accessory fluids; and finally the appearance of sexual instincts and inclinations. In the female, physical and functional maturity are almost contemi>oraneous, and functional woman- hood ceases siddenly at the menopause or climacteric. The change most characteristic of puberty in the female is the appearance of the menses', but besides this there are development of the breasts. oaries, uterus, and external gen- ital organs, and changes in the bony pelvis. In
