In this week’s parsha we learn some of the laws of kashrus. The Torah gives two
characteristics that a land animal must have in order to be kosher: split hooves and brings
up their cud. If a land animal has only one or neither of these characteristics it is not
kosher.

There is a machlokes as to the nature of the requirement of the characteristics of the land
animals. Are the characteristics (split hooves and bringing up its cud) an indication that
the species is kosher (siman), or is the actual possession of the character traits what
renders the animal kosher (seibah) regardless of the species.

The Maharit ( tishuva 51) says that the two characteristics are merely an indication that the species is kosher
and they are not the defining factor of kashrus. He brings a proof from the Mishnah in
Bichoros (5b) that says if a non kosher animal is born from a kosher animal the offspring
is kosher, and if a kosher animal is born from a non kosher one the baby is not kosher.
For example if a cow gives birth to a donkey the donkey is kosher, whereas if a donkey
gives birth to a cow the cow is not kosher. We see from this that an animal can be kosher
even though it lacks the two characteristics of kosher animals, therefore we can infer
that the character traits are not what make the animal kosher rather it is the fact that the
animal belongs to a kosher species.
The Maharit understands the mishnah that we determine an offspring’s species based
on the mother regardless of what the offspring looks like. Therefore if the mother is of
a kosher species, the baby will automatically be considered part of that species even if
it does not have the two characteristics of kosher animals. However there are achronim
who have another understanding of the mishnah as to why an offspring of a kosher
animal is kosher even when it resembles a non kosher species, and why an offspring of
a non kosher species is not kosher even when it resembles a kosher animal. They learn
that there is a new issur that applies to an animal that comes from a non kosher animal
even if the offspring has the characteristics of a kosher animal. Similarly, there is a heter
to eat an animal that comes from a kosher animal even if it does not possess the kosher
characteristics. According to these achronim the offspring does not assume the species
of its mother; rather it determines its own species based on its characteristics. However
even though it belongs to whichever species it most resembles, the mother does affect its
permissibility to be eaten.
According to the Maharit when a donkey gives birth to a cow, the cow is considered a
donkey and therefore not kosher. Whereas according to the second opinion the cow is a
cow however this cow is forbidden because it came from a non kosher animal.

One nafka meina (difference) between these two opinions is whether we can use the
hide of an offspring that is bearing non kosher signs who’s mother was a kosher animal,
for writing on them a sefer torah. If the animal is a non kosher species its hide may
not be used for writing a sefer Torah. If the animal is of a kosher species and is merely
forbidden to eat its hide may be used for writing a Sefer Torah.
The gimorah in Chullin (62 b) says that the male “swamp chicken” is forbidden but the
female “swamp hen” is permitted. Tosafos (d”h tarnigolsa) says the gimorah cannot
mean that the male of one species is non kosher and the female of that species is kosher
because the mishnah says if a kosher animal gives birth to a non kosher animal the
offspring is permited. So there can never be a non kosher male of these species since
they come from a kosher female mother. Therefore Tosafos explains that the gimorah is
referring to two separate species, and one is kosher both male and female, and one is non
kosher both male and female.

Tosafos in Nidah (50b) argues with Toasfos in Chullin and says the Gimorah is referring
to one species and the male is non kosher and the female is kosher. As to Tosafos in
chullin’s question from the mishnah, tosafos in niddah answers that the process in which
this species lays eggs is different from the norm in that the offspring do not directly come
from the mother rather they form on their own. Therefore the male of this species remains
non kosher even though it has a kosher mother.

Reb Ekchonon Wasserman zt”l Hy”d ( kovaitz shiurim chulin ois 27) explains that the
two tosfosim are essentially arguing the dispute mentioned above as to the nature of the
kosher characteristics. Tosafos in niddah is of the opinion that the kosher signs are what
makes an animal kosher and the lack of the signs is by definition a non kosher animal.
Therefore when a kosher animal gives birth to a non kosher animal the offspring should
be non kosher however since the mother was a kosher animal the offspring is permitted.
However that heter is only acquired when the offspring comes directly from the mother.
That is why tosafos says that since the offspring of this species does not come directly
from the mother it does not get that heter.
Tosafos in Chullin disagrees that the kosher signs serve only as an indication to what
species the animal belongs to, and we determine an animal’s specie by its mother.
Therefore this tosafos cannot offer the solution of tosafos in Niddah that the offspring
does not directly come from the mother because regardless we will define the specie
based on the mother and the male offspring will be kosher.
I would argue that perhaps Tosafos in Chullin can agree with Tosafos in Niddah because
the determination of the species should only follow the mother if the offspring comes
directly from the mother.