CHAPTEE VIII. 



EMBRYOLOGY. 



" My substance was not hid from thee when I was made in secret, and 

 curiously wrought in the lower parts of the earth. Thine eyes didst 

 see my substance, yet being imperfect, and in thy book all my members 

 were written, which in continuance were fashioned, when as yet there 

 was none of them." Ps. cxxxix. 15, 16. 



CLOSELY connected with Homology, and of equal 

 scientific importance, is Embryology. It is now 

 universally admitted that . embryological cha- 

 racters are frequently indispensable aids to 

 classification, and are often more useful in 

 indicating the proper position of an animal 

 in the scale of nature, than even a comparison 

 of the adult forms themselves. The simplest 

 of all existing living beings are the Monera,* 

 structureless atoms of sarcode in which even a 

 differentiation between an outer epidermis and 

 an inner nucleus does not appear to exist. 

 From these creatures we ascend in different 



* A translation of Haeckel's Monograph of this group, by the present 

 writer, will be found in the Quarterly Journal of Microscopical Science, 

 for 1869. 



