neuma； or spiritus； which was conveyed to the heart by the pulmonary vesselsone to the right； and one to the left side。 These vessels in the lungs； 〃through mutual contact〃 with the branches of the trachea； took in the pneuma。 A point of interest is that the windpipe；or trachea； is called 〃arteria；〃 both by Aristotle and by Hippocrates （〃Anatomy；〃 Littre； VIII； 539）。 It was the air…tube； disseminating the breath through the lungs。 We shall see in a few minutes how the term came to be applied to the arteries； as we know them。 The pulsation of the heart and arteries was regarded by Aristotle as a sort of ebullition in which the liquids were inflated by the vital or innate heat； the fires of which were cooled by the pneuma taken in by the lungs and carried to the heart by the pulmonary vessels。
＇29＇ De Generatione Animalium； Oxford translation； Bk。 II； Chap。 6； Works V； 743 a。
In Vol。 IV of Gomperz' 〃Greek Thinkers；〃 you will find an admirable discussion on Aristotle as an investigator of nature； and those of you who wish to study his natural history works more closely may do so easilyin the new translation which is in process of publication by the Clarendon Press； Oxford。 At the end of the chapter 〃De Respiratione〃in the 〃Parva Naturalia〃 （Oxford edition； 1908）； we have Aristotle's attitude towards medicine expressed in a way worthy of a son of the profession：
〃But health and disease also claim the attention of the scientist； and not merely of the physician； in so far as an account of their causes is concerned。 The extent to which these two differ and investigate diverse provinces must not escape us； since facts show that their inquiries are； at least to a certain extent； conterminous。 For physicians of culture and refinement make some mention of natural science；and claim to derive their principles from it； while the most accomplished investigators into nature generally push their studies so far as to conclude with an account of medical principles。〃 （Works； III；480 b。）
Theophrastus； a student of Aristotle and his successor； created the science of botany and made possible the pharmacologists of a few centuries later。 Some of you doubtless know him in another guiseas the author of the golden booklet on 〃Characters；〃 in which 〃the most eminent botanist of antiquity observes the doings of men with the keen and unerring vision of a natural historian〃 （Gomperz）。 In the Hippocratic writings； there are mentioned 236 plants； in the botany of Theophrastus； 455。 To one trait of master and pupil I must referthe human feeling； not alone of man for man； but a sympathy that even claims kinship with the animal world。 〃The spirit with which he （Theophrastus） regarded the animal world found no second expression till the present age〃 （Gomperz）。 Halliday； however；makes the statement that Porphyry＇30＇ goes as far as any modern humanitarian in preaching our duty towards animals。
＇30＇ W。 R。 Halliday： Greek Divination； London； Macmillan & Co。； 1913。
ALEXANDRIAN SCHOOL
FROM the death of Hippocrates about the year 375 B。C。 till the founding of the Alexandrian School； the physicians were engrossed largely in speculative views； and not much real progress was made； except in the matter of elaborating the humoral pathology。 Only three or four men of the first rank stand out in this period： Diocles the Carystian； 〃both in time and reputation next and second to Hippocrates〃 （Pliny）； a keen anatomist and an encyclopaedic writer； but only scanty fragments of his work remain。 In some ways the most important member of this group was Praxagoras； a native of Cos； about 340 B。C。 Aristotle； you remember； made no essential distinction between arteries and veins； both of which he held to contain blood： Praxagoras recognized that the pulsation was only in the arteries； and maintained that only the veins contained blood； and the arteries air。 As a rule the arteries are empty after death； and Praxagoras believed that they were filled with an aeriform fluid； a sort of pneuma； which was responsible for their pulsation。 The word arteria； which had already been applied to the trachea； as an air…containing tube； was then attached to the arteries； on account of the rough and uneven character of its walls the trachea was then called the arteria tracheia； or the rough air…tube。＇31a＇ We call it simply the trachea； but in French the word trachee…artere is still used。
＇31a＇ Galen： De usu partium； VII； Chaps。 8…9。
Praxagoras was one of the first to make an exhaustive study of the pulse； and he must have been a man of considerable clinical acumen；as well as boldness； to recommend in obstruction of the bowels the opening of the abdomen； removal of the obstructed portion and uniting the ends of the intestine by sutures。
After the death of Alexander； Egypt fell into the hands of his famous general； Ptolemy； under whose care the city became one of the most important on the Mediterranean。 He founded and maintained a museum； an establishment that corresponded very much to a modern university； for the study of literature； science and the arts。 Under his successors； particularly the third Ptolemy； the museum developed； more especially the library； which contained more than half a million volumes。 The teachers were drawn from all centres； and the names of the great Alexandrians are among the most famous in the history of human knowledge； including such men as Archimedes； Euclid； Strabo and Ptolemy。
In mechanics and physics； astronomy； mathematics and optics； the work of the Alexandrians constitutes the basis of a large part of our modern knowledge。 The school…boy of todayor at any rate of my daystudies the identical problems that were set by Euclid 300 B。C。； and the student of physics still turns to Archimedes and Heron； and the astronomer to Eratosthenes and Hipparchus。 To those of you who wish to get a brief review of the state of
science in the Alexandrian School I would recommend the chapter in Vol。 I of Dannemann's history。＇31＇
＇31＇ Friedrich Dannemann： Grundriss einer Geschichte der Naturwissenschaften； Vol。 I； 3d ed。； Leipzig； 1908。
Of special interest to us in Alexandria is the growth of the first great medical school of antiquity。 Could we have visited the famous museum about 300 B。C。； we should have found a medical school in full operation； with extensive laboratories； libraries and clinics。 Here for the first time the study of the structure of the human body reached its full development； till then barred everywhere by religious prejudice； but full permission was given by the Ptolemies to perform human dissection and； if we may credit some authors； even vivisection。 The original writings of the chief men of this school have not been preserved； but there is a possibility that any day a papyrus maybe found which will supplement the scrappy and imperfect knowledge afforded us by Pliny； Celsus and Galen。 The two most distinguished names are Herophiluswho； Pliny says； has the honor of being the first physician 〃who searched into the causes of disease〃 and Erasistratus。
Herophilus； ille anatomicorum coryphaeus； as Vesalius calls him； was a pupil of Praxagoras； and his name is still in everyday use by medical students； attached to the torcular Herophili。 Anatomy practically dates from these Alexandrines； who described the valves of the heart；the duodenum； and many of the important parts of the brain； they recognized the true significance of the nerves （which before their day had been confounded with the tendons）； distinguished between motor and sensory nerves； and regarded the brain as the seat of the perceptive faculties and voluntary action。 Herophilus counted the pulse； using the water…clock for the purpose； and made many subtle analyses of its rate and rhythm； and； influenced by the musical theories of the period； he built up a rhythmical pulse lore which continued in medicine until recent times。 He was a skilful practitioner and to him is ascribed the statement that drugs are the hands of the gods。 There is a very modern flavor to his oft…quoted expression that the best physician was the man who was able to distinguish between the possible and the impossible。
Erasistratus elaborated the view of the pneuma； one form of which he believed came from the inspired air； and passed to the left side of the heart and to the arteries of the body。 It was the cause of the heart…beat and the source of the innate heat of the body； and it maintained the processes of digestion and nutrition。 This was the vital spirit； the animal spirit was elaborated in the brain； chiefly in the ventricles； and sent by the nerves to all parts of the body； endowing the individual with life and perception and motion。 In this way a great division was made between the two functions of the body； and two sets of organs： in the vascular system； the heart and arteries and abdominal organs； life was controlled by the vital spirits； on the other hand； in the nervous system were elaborated the animal spirits； controlling motion； sensation and the various special senses。 These views on the vital and animal spirits held unquestioned sway until well into the eighteenth century； and we still； in a measure； express the views of the great Alexandrian when we speak of 〃high〃 or 〃low〃 spirits。
GALEN
PERGAMON has become little more than a name associated in our memory with the fulminations of St。 John against the seven churches of Asia； and on hearing the chapter read； we wondered what was 〃Satan's seat〃 and who were the 〃Nicolaitanes〃 whose doctrine he so hated。 Renewed interest has been aroused in the story of its growth and of its intellectual rivalry with Alexandria since the wonderful discoveries by German archaeologists which have enabled us actually to see this great Ionian capital； and even the 〃seat of Satan。〃 The illustration here shown is of the famous city； in which you can see the Temple of Athena Polis on the rock； and the amphitheatre。It s interest for us is connected with the greatest name； after Hippocrates； in Greek medicine； that of Galen； born at Pergamon A。 D。 130； in whom was united as never before and indeed one may say； never sincethe treble combination of observer； experimenter and philosopher。 His father； Nikon； a prosperous architect； was urged in