CEHTAIX CROSSINGS <u . I \r\\i-i i,.,\i 



This group of hybrids showed nl.-o ill-adjusted reproductive mttittd The 

 records of ."> pairs of lliesc hybrids, or of ;i hybrid mated to :i |i;ircnl form. an- iiiveti 

 herewith. In all of lliesc I here is a history, usually quite per-i-ten! 

 eggs or young. This desertion of the nest is more frequently met \\ilh in the hybrid- 

 than in either of the parent species. Soft -slid led eggs are noted in L' of the.") matr 

 a dwarf egg in 1. The meaning of these re|irodnei ive abnormalit i< - j. ,,,,! r 

 but their incidence in individuals or generations who-e '^Tin-cell- are aNo ill- 

 adjusted" inei'ils further consideration. 



A brother and sister from the ' lurliir x 9 oriuilulix cn>. uen- mated when 

 a little less than 1 year old. This pair (')) produced 1 I eggB during their lir-t 

 (immature) year. Table II shows the consistently poor result-: I e- <;a\.- no 

 embryo, 1 a weak embryo, ~> produced embryos but the eg- \\ere de-erled and 

 were not given a complete test, (i hatched, 1 lived but 1(1 day>, \\hile the remaining 

 5 all died between I mont h and 2.1 months after hatching. I hiring the follou ing 

 year the pair produced 1 1 eggs, of which X were toted ; 2 failed to produce emb 

 and were hatched; all except 1 lived 2 to 5 months; the exception lived 22 

 months. The pair evidently produced stronger germs when 2 year- old than when 

 in their first year. The sex of 9 of the young is known :'. males and (i femal' 



Asistertothe birds of pair 5 just described was mated to a male of the on Ht 

 liniiir cross. This pair ((i) was more mature when mated, but per-i.-tent desert inn 

 of eggs (see table 12) permitted only I adequate tests of t he 111 eg",.- produced during 

 two years; 2 of these (and also 2 deserted ones) produced embryo-, and 2 hatched. 

 One of the latter was a male which lived 4 months. 



A brother to the male of pair (i was tested when 1 year old with a pure .lapane-e 

 female. From 8 tests (11 eggs) i! young were hatched with life-term- of '.'> di 

 2 months, and 10 months. In their second, more mature, year they .-main yielded 

 11 eggs; of these 8 hatched and 3 were quite infertile. Three died early. 1 lived :; 

 to 8 months, and 1 is still alive at nearly S years (table ]'>>. T\\o male- and :i 

 females are known from the eggs of the second year. The better result from the 

 more mature birds is obvious. 



A male orientalix x furfur hybrid was mated when I year old to a : , ! n'i ntnlis 

 \ liirlur hybrid hatched from the preceding pair (6). The result is a demonstration 

 of still lower fertility and a still further restriction upon the life-term of offspring 

 than pertains to cither of the earlier crosses from which the two parents wen- 

 produced. Table 14 indicates 11 tested eggs; of these I are known to have been 

 absolutely infertile; 1 gave an embryo only, (i eggs hatched, but the term of life 

 of probably all of them was between 5 days and 2.' months i table 1 1 . None of 

 the hybrids from the orientalis-turtur crosses tested infertile. 



The following cross is of unusual interest. A hybrid from two race- of common 

 pigeons was mated with a female titrlnr x oriental!* hybrid. Here the two indi- 

 viduals finally crossed are widely separated forms, but in addition cadi parent i- 

 itself a hybrid from two closely related species or varieties common ]< 

 Attention may first be given to the fact that color in the offspring is here a 

 limited character, the males being dark, the females light in color. Then- is one 

 apparent exception for each sex. The female that was not of light color \\ a- 'dark 



* For treatment of several relaleil tuple- H6 "The Rrpnxluetive Cyele." Vol. Ill .if lln-x- ,.rk~. 



