a ol = 
97 
On Some Features in the Hereditary Transmission of the Self- 
black and the “ Irish” Coat Characters in Rats.—Paper I. 
By Geo. P. Mupcez, A.R.C.8ce. Lond., F.Z.S., Lecturer on Biology, London 
Hospital Medical College (University of London), and the London 
School of Medicine for Women (University of London), 
(Communicated by A. D. Waller, F.R.S. Received May 8,—Read November 14, 
1907.) 
CONTENTS. 
PAGE 
PAPAL OCHINCEOIY) we. Sion) cna wae seed tine aaeenbae Met aad Ss noacusessa ye Vanutacks 97 
B. System of Interpretation of Results..............ccceccecsceeeseeees 99 
€. The “ Irish” Character : Nature and Origin .................0005 100 
i yeeeperimental Results 1.21.15. gsi deonsccerecisestnencestisrasearesdace cuss 102 
Cie trish sb Olbish OG GO CEG. b) saci seckscenccsacess 102 
Ge AMIN GE PAR CMCAQ Es cece. ti stv ences: davcaracceevessadubissaves 102 
CDOeEte bale Pare med ee 500.5 j. cieetedsacslvvedewete steeds ies 104 
(2) “Irish” 6x Piebald black-white (Cr 6 bx Cr 5) ......... 105 
(3) i Mp lmian(Or 6 Doc Cr 4.6 oot lswentecea cess 106 
(4) is x Grey with White (Cr6 6x Cr 2) | .....cccess. 108 
(oP Ayecovic, pattern” albtnOes v2.20: 2.<casebescecasgeceeees cheeee Vat 
(o) Self-black'® albine (Cr 7 & Cr 4) ik idsecliksesscdsaecesensed 112 
(a): Black var. 7 wildigrey x albino: ...2..:-.crcacsieseensss 112 
(b) Extracted self-black x albino .........s:0sccssesesseeves 113 
Ci) me OUTRAGE OE MUCSULES ad isaices at dus oo sinntsic velsnneiele Stee wate cie 115 
A. INTRODUCTORY. 
In 1903 I commenced a series of breeding experiments with rats. They 
were undertaken with the object of ascertaining whether Mendel’s Principles 
would adequately interpret the observed facts. 
During the interval of four years which has since elapsed, many records of 
results have been made. But a consideration of these initial results shows 
that the problems involved are of some complexity, and many years of 
continuous work will be needed before the hypothetical assumptions, which 
tentatively have had to be adopted, can be regarded as proved. Notwith- 
standing this, it can be shown by the whole of the results so far reached— 
only part of which are here recorded—that the phenomena may be explained 
on the basis of segregation, gametic purity, and of dominance, if we tenta- 
tively accept certain postulates which are enumerated below (infra, p. 99). 
I purpose describing my results in a series of separate papers, of which this 
is the first. . 
At the time that my experiments were undertaken, the only papers which 
had been published on the hereditary transmission of coat colours in rats 
