Earlj Development of the Hen's Egg. 105 



There are but few hens that ever lay before 8 :00 a.m. or after 

 4 P.M. It is evident, therefore, that a hen in laying daily will 

 eventually come to the 4 o'clock period, and will then miss a day 

 (sometimes more) before beginning a new set. Indeed, this is true 

 for all hens whether laying regularly or irregularly, for they lay 

 in a sort of rhythm. In the case of irregular laying, cited above 

 (hen 3), the eggs laid from the 25th of July (when the observa- 

 tions were begun) to the 1st of August, are the last of a set in which 

 the hen was laying approximately every other day; while those 

 laid from August 6th to 18th constitute another set. Evidence that 

 the eggs will be laid in sets can be obtained by an examination of 

 the ovary, which shows several graduate series of ovarian eggs. 



It will be evident from the above considerations and data that if 

 one is to secure a close series, it is necessary to study each hen in- 

 dividually and while this involves a great amount of labor, yet it is 

 the only way in which one is able to meet with any success. 



The collecting of the above data has another advantage besides 

 that of aiding in securing a close series, for it makes possible the. 

 determination of the rate of development of the different stages. The 

 time occupied by the egg in passing down the oviduct has been 

 variously estimated at from eighteen to twenty-four hours, and even 

 •as high as thirty-six hours.- This seems like a wide variation, and 

 in taking up this work, the writer was prepared to find the normal 

 time more constant than is indicated in such estimates. 



The writer finds that in a hen kept under normal conditions, the 

 egg traverses the entire length of the oviduct in about twenty-two 

 hours. The time occupied in the different portions of the oviduct 

 is as follows : Glandular portion, three hours ; isthmus, two to three 

 hours; uterus and laying, sixteen to seventeen hours. 



As just stated, these estimates were made on hens kept under 

 normal conditions ; that is, hens that were given the freedom of the 

 barnyard. It is possible to lengthen the time beyond the twenty- 

 two hours by disturbing the hen when she is about to lay, and on one 

 occasion the writer was able to delay the laying of the egg for 

 twenty hours. When it was finally deposited an examination re- 

 vealed the fact that it was in a stage of development equal to about 

 twenty hours of incubation. This would account for the high esti- 



