INFLUENCE OF SPERMATOZOA ON UATE OF DEVELOPMENT OF EMBRYO. 203 



a certain number of hours. The male has not very much prolonged the period of 

 incubation, but before I can say he has not affected it I have to consider the facts to 

 be learned from the reciprocal cross, from crosses made simultaneously, if possible, 

 and from crosses of still other species. 



TABLE 180. Incubation period of <f archangel (Ar 1) x 9 ring-doves (D 1 and I) 2). 



Summary: Time, Feb. 18, 1897, to Mar. IS'JS. Of 24 eggs, 2 hatched, fertilized; none reared. 



1 Some data referred to in various chapters of Vol. Ill are presented in connection with this and succeeding tables. 



EDITOR. 



TABLE 181. Incubation period of & black Japanese tumbler (T 3) X 9 ring-dove (L. I). 



Summary: Time, July Ib97, to March 1898; 10 eggs; reared 5, hutched 7, 10 fertilized. (A 15} 



1 Hatched only with help and soon died; the hatching was abnormally delayed, perhaps from imperfect development. 



