122 



AGE, GROWTH, AND DEATH 



with one another, to realise that the progress of the 

 embryo in size and development proceeds with a 

 rapidity which is never to be found in later stages. 



The history of embryonic rabbits declares with 

 equal emphasis that the earliest development is ex- 

 tremely rapid. I wish now to show you a series of 

 pictures to illustrate in the same manner the pro- 

 gressive development of the rabbit. Numbers one to 

 five of the figures upon the screen represent what is 

 known as the germinal area, in the centre of which 

 the actual embryo is gradually formed. In No. i 

 merely the axis is indicated, in front of and alongside 

 of which the parts of the embryo are to arise, as is 

 suggested by Nos. 2, 3, 4, 5. These stages cover the 

 seventh and eighth days. Nos. 6 to 14 figure actual 

 embryos, No. 6 of nine and a half, No. 14 of fifteen 

 days. No. 6 is singularly twisted into a spiral form, 

 the reason for which is still undiscovered. No. 9 

 shows the condition at eleven days notice the limbs, 

 a leg in front and a leg behind, each only a small 

 mound as yet upon the surface of the body ; the dis- 



EXPLANATION OF FlG. 44. 



FOURTEEN STAGES OF THE DEVELOPING RABBIT, after Minot's and 

 Taylor's "Normal Plates." All the figures are magnified four diameters. 

 Nos. 2 to 5 are irregular as to age, but show successive stages of development. 

 The early development is extremely variable and the observations do not yet 

 suffice to determine the average typical condition for each day under nine. 

 No. I. Embryo of j)4 days. No. 8. Embryo of 10^ days. 



No. 2. 

 No. 3. 

 No. 4. 

 No. 5. 

 No. 6. 

 No. 7. 



10 



No. 9. 

 No. 10. 

 No. ir. 

 No. 12. 



No. 13. 

 No.. 14. 



13 



15 



