66．In fact，throughout the animal kingdom，from sponges to certain types of worms，shellfish，and all vertebrates(creatures possessing a spinal column), there isevidence that transplants of cells or fragments of tissues into an animal areaccepted only if they come from genetically compatible or closely relatedindividuals．

(从句that transplants…are accepted…作evidence的同位语)

实际上，从海绵到某些种类的蠕虫、有壳的水生动物和所有的脊椎动物(有脊柱的生物)的整个动物界都有证据表明，进入动物体的细胞或组织片断移植只有在来自基因上相容或关系密切的个体时才被接受。

分句1. In fact，throughout the animal kingdom，from sponges to certain types ofworms，shellfish，and all vertebrates(creatures possessinga spinal column)，

分句2. there isevidence

分句3. transplants of cells or fragments of tissues into an animal are accepted onlyif they come from genetically compatible or closely related individuals

1和2嵌套

2和3嵌套