284 Referate. 



DD Ee A A ones. If A be absent, the animal is black (in this series) and 

 the addition of D has no visible effect. 



Punnett now found a black male, whose gametic constitution must 

 have been Dd Ee Aa. He mated this male to several dd Ee aa females. 

 On the supposition that in the formation of gametes by this male the 

 factors D and E are coupled, we ought to get : i DdEEÄa (agoutiblack), 

 I DdEEaa (black), i DdEeAa (black), i DdEeaa (black), i ddEeAa (agouti), 

 n ddEeaa (black), i ddeeAa (Yellow) and i ddeeaa (tortoise), or agouti), 

 black, agouti-black, yellow and tortoise in the ratio 1:4:1:1:1. The 

 actual numbers were : 



Punnett could further show that in reality all the yellows were 

 heterozygous for A (nine were tested); further that all of seven agoutis 

 tested were heterozygous for both A and E, and that several agoutiblacks 

 tested were homoz3'gous for E but heterozygous for D and A. 



The methods of testing adopted were always back-crossings to animals 

 lacking the factors for which the individual was to be tested. In my 

 work with the factors which influence the colour in mice, I have always 

 followed this same scheme, in preference to random matings of to be 

 tested animals inter se. It is evident that several difficult questions can 

 only be answered in this way. 



It seems that the coupling between the two factors in Punnet t's 

 rabbit was complete, just as in all the cases of coupiling or repulsion 

 studied in animals. Two cases of coupling and one of repulsion are now 

 on record in animals concerning factors without relation to sex, the 

 repulsion being a case I found in mice, the second case of coupling being 

 found by Morgan in Drosophila. Hagedoorn. 



Haecker, V. Über Kreuzungsversuche mit Himalaya- und Black-and-tan- 

 Kaninchen. Mitt. Nat. Ges. Halle a/S. 2 1912. 



Reziproke Kreuzung zwischen Himalaya-Kaniiichen (-akromelanistische 

 Albinos mit farbigen Abzeichen an Nase, Ohren, Pfoten und Schwanz) und 

 Black-and-tan-Kaninchen (-schwarze Grundfarbe mit lohfarbenen und weißen 

 Abzeichen) ergab in Fi ,, abgeänderte" Black-and-tans; in Fo dreierlei Nach- 

 kommen: I. ,, abgeänderte" Black-and-tan; 2. schwarze Tiere; 3. ,, ab- 

 geänderte" Himalayas. 



Die abgeänderten Black-and-tans zeigen an Stelle der ausgebreiteten 

 lohfarbenen Zeichnung eine weniger ausgebreitete und gelbliche, und zwar 

 in verschiedener Intensität und Ausdehnung. Fi und Fo verhalten sich 

 hierin gleich. Die abgeänderten Himalayas sind gegenüber den reinrassigen 

 Tieren dadurch ausgezeichnet, ,,daß sie in der weißen Umrandung der 

 Nasenlöcher und in der geflammten Zeichnung der Pfoten ausgesprochene 

 Erbteile der Black-and-tans mit sich führen" 



In Fl also „unvollkommene Dominanz" der Black-and-tan Färbung, in 

 F.2 bei der Kategorie der abgeänderten Himalaya ,, deutliche Beeinflussung 

 in ihrer Zeichnung durch die black-and-tanf arbigen Aszendenten". 



M. Daiber (Zürich). 



