In spite, therefore, of the encyclopaedic tradition which has persisted from Aristotle through the Arab and medieval schools down to Herbert Spencer, it is forced upon us in our own day that in a pursuit so manysided as medicine, whether in its scientific or in its practical aspect, we have to submit more and more to that division of labour which has been a condition of advance in all other walks of life.
In the towns the division of labour had proceeded much further than in the rural districts, and there were in existence organized bodies, such as the Gild Merchant and the crafts, whose functions were primarily economic. But one of the most striking characteristics of town life in the middle ages was the manner in which municipal and industrial privileges and responsibilities were interwoven.
Balfour put forward the view that the polyp was the more primitive type, and that the medusa is a special modification of the polyp for reproductive purposes, the result of division of labour in a polypcolony, whereby special reproductive persons become detached and acquire organs of locomotion for spreading the species.
The division of labour among the two castes of female becomes therefore most complete in the most highly organized society.
In modern times two factors have accelerated this process, viz.: (I) the building of railways, which have developed commerce to a very great degree and favoured the large towns at the expense of the small; and (2) the invention of machinery, which has greatly increased the possibility of division of labour and manufactures on a large scale.
On a direct-fired furnace at least one man, the brigadier, must be an expert in all the operations involved; but with a gas furnace a division of labour is possible.
The specialization which accompanies the division of labour has important geographical consequences, for it necessitates communi 1 On the influence of land on people see Shaler, Nature and Man in America (New York and London, 1892); and Ellen C. Semple's American History and its Geographic Conditions (Boston, 3903).