THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 231 



sion of animals in geological time. First, we may learn 

 that tlie plan of creation has been progressive, that there 

 has been an advance from the few, low, and generalized 

 types of the primaeval ocean to the more numerous, 

 higher, and more specialized types of more recent 

 times. Secondly, we learn that the lower types, when 

 first introduced, and before they were subordinated to 

 higher forms of life, existed in some of their grandest 

 modifications as to form and complexity, and that in 

 succeeding ages, when higher types were replacing 

 them, they were subjected to decay and degeneracy. 

 Thirdly, we learn that while the species has a limited 

 term of existence in geological time, any grand type of 

 animal existence, like that of the Foraminifera or 

 Sponges, for example, once introduced, continues and 

 finds throughout all the vicissitudes of the earth some 

 appropriate residence. Fourthly, as to the mode of 

 introduction of new types, or whether such creatures 

 as Eozoon had any direct connection with the subse- 

 quent introduction of mollusks, worms, or crustaceans, 

 it is altogether silent, nor can it predict anything as to 

 the order or manner of their introduction. 



Had we been permitted to visit the Laurentian seas, 

 and to study Eozoon and its contemporary Protozoa 

 when alive, it is plain that we could not have foreseen 

 or predicted from the consideration of such organisms 

 the future development of life. No amount of study 

 of the prototypal Foraminifer could have led us dis- 

 tinctly to the conception of even a Sponge or a Polyp, 

 much less of any of the higher animals. Why is this ? 



