393 
Cross Fer tinizATION AmMonc FISHES. 
By W. J. MoENKHAUS, INDIANA UNIVERSITY, BLOOMINGTON, INDIANA. 
CONTENTS. 
PAGE 
ROME Olay eae Pmreets = xO Ss0c on caste Screg SU Medeira enaicl cis SSN Ae ae eae 353 
EDSIOMeH Ay Sees eee EE IAA SS OMe Bu ate ae Aten ot A A 354 
silcore] ny16 bse lahat Ros eee aoe ee Ree bahia Peis 2 MRCS RNS 1505) 
[Des isreiniyourieyal, C1) CROSSES eae aetna siete eR rete el eee» Ullah lh ve 356 
Summary of Experiments— 
BARRON CHIC GOSTUV ETE i oo. Ss aren, OR eed. te aled. «dts, 4 24s Ree oe 378 
inamcreron- lnprepmabion:...)2 57.2 ess. sas oe ba J Le ee 378 
ERCeMA COLO MeRGiM A DELON ent as, 60.2 sogveacsce nels» a etree es ea eee 378 
Peel Ome mite IED Uaed ct ciao MRSS nates ctonag ss c nyadlva Bia st, fA aaah ep a eae ee 379 
General and Theoretical Considerations— 
PCMCIAN ME THU AGU E08 2 2558s clei G)«, aay) dene 3) ys pe ate aeons © ok eel Se 384 
Degree of Development and Systematic Relations..................... 385 
SIMEON? 31g dt Ale dencies Hid kaa ae ne a een Seer rei ee ARPA Manet SERA ua INL! 391 
TBigen a ECMO Te Ces n att Ne fk SNe tabla le cledsa bacco (aid Rune Ae ee maT a Ee rN 392 
INTRODUCTORY. 
In the following pages I wish to record the more important results 
of my experiments in the cross-fertilization of fishes. These have been in 
progress more or less continuously since 1898. These experiments were 
originally undertaken with quite another object in view, namely, for inherit- 
ance and cytological studies. A survey of available nearly related forms 
was made that would successfully hybridize for variation and inheritance 
studies. Another purpose was the hybridization of forms with different 
shaped chromosomes, so that the behavior of the latter could be followed in 
development. It soon developed that the possibility of cross-fertilizing 
fishes was very much greater than had hitherto been supposed. This led 
ine to seek all possible combinations of species of whatever relationship 
[23—26988 ] 
