Selected Reform Responsa 225

to rest on shabbat as human beings(Ex. 20.10; 23.12; Deut . 5.14). Provisions were made for animal care on shabbat, an animal which was normally milked by a non-Jew . If an animal needed to be rescued it was to be done even on shabbat(Shab. 128a; Yad Hil. Shabbat 25.26;1 Shulhan Arukh Orah Hayim 305.19). We should also note that the castration of animals was prohibited and this has always been considered as a form of maiming, which was forbidden(Shelat Yaabetz 1.11). We may summarize this by relating that our tradition demands kind treatment of animals. They may be used by human beings but not treated cruelly. We should note that the medieval discussion by some Jewish philosophers about the soul of animals was left as a speculative issue.

Now let us deal with genetically induced changes in mice which are to be used as experimental animals. Systemic genetic dianges are a recent scientific achievement. The only area which approached this field in the'past was controlled breeding. Our tradition had very little to say about breeding animals as long as no attempt was made to do so with unlike species. There was a great interest in maintaining species of both plants and animals separately, based in part on Biblical verses(Lev. 19.19: Deut. 22. 10). An entire section of the Mishnah (Kilaim) dealt with the problem of mixing various kinds of seeds together, grafting one plant onto other and interbreeding of animals. This segment of the Mishnah contains eight chapters which dealt with various kinds of mixtures such as the prohibition against interweaving wool and linen and comment and to the best of my knowledge do not use it as an example of animal breeding. There were occasional commentaries like Ramban who stated that human beings should not change nature as that would imply imperfection in God 's creation(Ramban to Lev. 19.19) That medieval view was found frequently in church literature. It has not been followed by Jewish thinkers.;

Jewish law said nothing about changing the characteris particular species or breed. Throughout the centuries every effort was made to assist nature and to produce animals suited to specific gin or for special reasons like Jacob and his flock(Gen. 30:29 ff) as well as plants which would yield abundantly. Despite Jewish involvement In

tics of a