SECT, i] EMBRYOLOGY IN ANTIQUITY 47 



time. In Upper Egypt there are over fifty establishments, and in 

 Lower Egypt more than a hundred. The furnace is constructed of 

 sun-dried bricks and consists of two parallel rows of small ovens and 

 cells for fire divided by a narrow vaulted passage, each oven being 

 about 9 or 10 feet long, 8 feet wide and 5 or 6 feet high, and having 

 above it a vaulted fire-cell of the same size but rather less in height. 

 The eggs are placed upon mats or straw, one tier above another 

 usually to the number of three tiers and the burning fuel is placed 

 upon the floors of the fire-cells above. The entrance of the furnace is 

 well closed. Each furnace consists of from twelve to 24 ovens and 

 receives about 150,000 eggs during the annual period of its con- 

 tinuing open, one quarter or one third of which generally fail. The 

 peasants supply the eggs and the attendants examine them and after- 

 wards generally give one chicken for every two eggs that they have 

 received. The general heat maintained during the process is from 

 100 to 103 of Fahrenheit's thermometer. The manager, having been 

 accustomed to the art from his youth, knows from long experience 

 the exact temperature that is required for the success of the operation 

 without having any instrument like our thermometer to guide him. 

 The eggs hatch after exactly the same period as in the case of natural 

 incubation. I have not found that the fowls produced in this manner 

 are inferior in point of flavour or in other respects to those produced 

 from the egg in the ordinary way." The accompanying picture 

 (Plate I a), taken from Cadman, shows the interior of a modern 

 peasant's incubator. There is reason to beheve that its construction 

 and operation vary very little, if at all, from that of the ovens used in 

 dynastic Egypt. 



When Bay visited the native incubators in 191 2 he took with him 

 a flask of lime water and a thermometer. The former showed a large 

 precipitation of calcium carbonate and the latter stood at 40° C. He 

 was led to speculate on the value of a high CO2 tension in the at- 

 mosphere, and concluded that it must have a beneficial effect, since 

 the loss in the native incubator was not more than 4 per cent., while 

 that in the oil-heated agricultural incubators of his time was as 

 much as 40 per cent. Cadman, writing in 1921, suggests that the 

 well-known non-sitting instinct of Egyptian poultry is an effect of 

 the ancient practice of artificial incubation. But enough has been 

 said of the Egyptian "Ma'mal al katakeet", or chicken factory. 

 In spite of the remarkable opportunity thus afforded for acquiring 



