Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!casbah.acns.nwu.edu!nucsrl!tellab5!wheaton!lpsmith
From: lpsmith@wheaton.uucp (Lucian P. Smith)
Newsgroups: sci.bio
Subject: Re: Cats and Rabbits
Keywords: Palindrome
Message-ID: <1991Apr30.170456.1276@wheaton.uucp>
Date: 30 Apr 91 17:04:56 GMT
References: <1991Apr28.152146.1353@usenet.ins.cwru.edu> <42178@netnews.upenn.edu>
Reply-To: lpsmith@wheaton.UUCP (Lucian P. Smith)
Organization: Wheaton College, IL
Lines: 40

In article <42178@netnews.upenn.edu> rowe@pender.ee.upenn.edu (Mickey Rowe) writes:
>In article <1991Apr28.152146.1353@usenet.ins.cwru.edu> axa12@po.CWRU.Edu (Ashok Aiyar) writes:
>>
>> (stuff deleted)

>>Also I would be interested in knowing about other inter-species
>>offspring such as "tigons", "ligers" and "mules".
>

(more stuff deleted)
>
>Mules are crosses between horses and donkeys.  They are canonically
>sterile, but I have a hazy memory that this isn't always the case
>(though I'm sure it is in the vast majority of such pairings...)
>
>>Ashok Aiyar
>
>Mickey Rowe    (rowe@pender.ee.upenn.edu)

My biology textbook explained why mules are sterile.  Apparantly, horses have
two more chromosomes than donkeys, and therefore the resultant mules have an
odd number of chromosomes (I believe 33) and meiosis doesn't work.  (This is
somewhat hazy to me; it would seem like a mule could produce either donkeys or
horses depending on the chance occurence in meiosis, but anyway,...)

Every so often, disjuction (?) occurs in the parents of the mule, and the mule
is left with an even number of chromosomes, and is fertile!  The book mentions
one such case somewhere (I forget the exact case, though I could look it up if
anyone is interested.)  This is, of course, very rare; the russian expression
for "Once in a blue moon" is something like, "When a mule foals."  :-)

HAND.  (Have A Nice Day)

-Lucian

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"Do good?  I?  No!  Evil anon I deliver.  I maim nine more hero-men in Saginaw,
sanitary sword a-tuck, Carol, I--lo!--Rack, cut a drowsy rat in Aswan.  I gas
nine more hero-men in Miami.  Reviled, I (Nona) live on.  I do, O God!"
~~~~tellab5.chi.il.us!wheaton!lpsmith@gargoyle.uchicago.edu~~~~~~~~~~~~~~~~~~~~~