EAELT STAGES OF DEVELOPMENT OF THE RABBIT. 161 



backed/' and the joining strands are curved and even arch 

 away from the epiblast^ and in some cases undoubtedly the 

 cells themselves seem to stand away from the surface. 



It is, however, quite possible that the sinuosity of the line and 

 arching away may be the result of reagents, as I have not 

 examined this edge in a fresh specimen with success. 



EXPLANATION OF PLATES 13—17, 



Illustrating Mr. Richard Assheton^s paper, " A Re-investigation 

 into the Early Stages of the Development of the Rabbit.^' 



List of Reference Letters. 



A. Anterior end of blastodermic vesicle. ALB. Albuminous layer acquired 

 in Fallopian tube. C, BL. Cavity of blastodermic vesicle. EM. 1). Embryonic 

 disc. EP. I. Inner layer of epiblast. EP. 0. Outer layer of epiblast. 

 EP. OH. Cell of outer layer of epiblast becoming " accidentally " included 

 in the inner layer of epiblast. HF. Hypoblast of embryonic disc. HT. L 

 Hypoblast of region beyond embryonic disc. I. M. Inner mass of cells of 

 blastodermic vesicle. L. Larger of the first two segments. Z-. Supposed 

 second generation of layer of first two segments. L^. Supposed third genera- 

 tion of layer of first two segments. 0. L. Outer layer of cells of blastodermic 

 vesicle. P. Posterior end of blastodermic vesicle. P. B. Polar body acci- 

 dentally enclosed. PL. S. Sinuous protoplasmic junction between two hypo- 

 blast cells. S. Smaller of the first two segments. S". Supposed second 

 generation of smaller of first two segments. S^. Supposed third generation 

 of smaller of first two segments, x., x^. Deceptive appearances suggesting a 

 van Beneden blastopore. Z. Zona radiata. 



All the figures excepting Pigs. 37, 38, and 41 have been drawn with the 

 help of a camera. 



All those figures of which the magnification is 465 times were drawn with 

 Powell and Lealand's ^ apochromatic oil immersion ; the others with Zeiss or 

 Reichert's lenses. 



VOL. 37, PART 2. — NEW SEE. L 



