3/2 ALBERT C. EYCLESHVMER. 



A second method of increasing the supply of air was to re- 

 move whole pieces of the shell. Of course great care was taken 

 not to injure the shell membrane or growing blastoderm. This 

 fracture was made some distance from the embryo, so that the 

 drying could not extend to the embryo, and the egg after the re- 

 moval of the part of the shell was turned so that the broken 

 portion was downward. The embryo was perfectly formed, but 

 grew at the same astonishingly rapid rate. 



The above consideration led to the conviction that artificial 

 incubation can only proceed where there is an abundant supply 

 of fresh air (oxygen). In order to confirm this supposition, the 

 following experiment was tried. 



Experiments. - - Two incubators with similar ventilating sys- 

 tems, which, however, were believed to be inadequate, were 

 employed. One was left with the ventilating system unmodified. 

 The other was provided with two one-inch intake pipes. These 

 extended to the outside of the building in which the incubators 

 were located, and so arranged that a continuous current of fresh 

 air passed into the egg-chamber. 



Two egg trays of 100 capacity each, were filled with eggs 

 from the same lots of fowls ; special care being taken to divide 

 the eggs from each flock so that there should be an equal num- 

 ber in each tray. The eggs were then subjected to exactly the 

 same treatment, barring slight variations in temperature which 

 necessarily existed. 



On the fifth day the eggs were tested, and from the incubator 

 with special ventilation, sixteen (infertile) eggs were removed. 

 From the other, twelve (infertile) eggs were removed. On the 

 twelfth day they were again examined. From the incubator with 

 special ventilation seven dead embryos were removed and from the 

 other, twenty. From the eighty-four in the incubator with special 

 ventilation, seventy- two hatched, while five were dead in the shell, 

 giving a percentage of 85.7 per cent, hatched from the fertile eggs. 

 Of the eighty-eight eggs remaining in the other incubator, but 

 thirty-nine hatched ; a number of the remainder pipped, just how 

 many was not recorded, while a large number were dead in the 

 shell. There was thus hatched in the incubator without venti- 

 lation 44.3 per cent, of the fertile eggs. 



