298 EMBRYOLOGY AND CLASSIFICATION. 



of his arteries may not disturb the steadiness 

 of his gaze, and the condition of his nervous 

 system be so calm that his whole figure will re 

 main for hours in rigid obedience to his fixed 

 and concentrated gaze. 



After these remarks I trust I shall not be mis- 

 understood by those who have been working in 

 the field of microscopic investigation, and for 

 whose persevering devotion no one can feel a 

 deeper reverence than I do, if I add that there 

 is as yet hardly a beginning in the study of the 

 egg during its growth, and anterior to the for- 

 mation of the germ. Since Embryology became 

 a science, the great aim of students in that de- 

 partment lias been to demonstrate the uniform 

 structure of the egg in all animals, and investi- 

 gators have limited their observations to that 

 stage of the ovarian egg during which it ap- 

 pears in all animals as a perfect cell. But a 

 new field now opens before us, requiring a care- 

 ful survey of every stage of growth of the egg, 

 from its first formation to the period when a 

 well-dofined germ is developed. The growth of 

 the egg during this period requires to be studied 

 as minutely through all its changes, and in the 

 various combinations of its constitutive elements, 

 as the germ itself has been in its later trans- 

 formations. Here again, in this later phase, 

 another field presents itself equally new and 



