374 G. HAROLD DREW 



Morgan, T. H. 1904 Germ layers and regeneration. Archiv fur Entwickl.- 

 mech. der Organismen, vol. 18, no. 2. 



RiBBERT, H. 1904 Geschwulstlehre, Bonn. 



Saxer, F. 1904 Ziegler's Beitrage, vol. 38. 



TowLE, E. W. 1891 On Muscle regeneration in the limbs of Plethodon. Biol. 

 Bull. II. 



Wolff, G. 1893. Entwickelungphysiologische. Studien 1. Die Regeneration 

 der Urodelenlinse. Arch, fur Entwickl.-mech. der Organismen, vol. 1. 

 1894 Bemerkungen zum Darwinismus, mit einem experimentellen 

 Beitrag zur Physiologie der Entwickelung. Biol. Centralb., vol. 14. 



PLATE 1 



EXPLANATION OF FIGURES 



1 Stages in division of a normal fibroblast. X 1000. 



2 Portion of a cyst wall after 5 days. Below is the degenerating ovarian tissue 

 invaded by phagocytes, and this is divided from the muscle by several layers 

 of fibroblasts, mostly in the active state. Above is a blood space bounded by fib- 

 rous tissue, some of the fibroblasts of which are dividing. X 800. 



3 Portion of a cyst wall after 20 days. The ovarian tissue has completely de- 

 generated. The inner fibroblasts have changed the character of their nuclei and 

 become connected by a continuous layer of cytoplasm. X 800. 



REFERENCE LETTERS 



b.c. Blood corpuscles. div.fbl. Dividing fibroblasts. 



b.sin. Blood sinus. fbl. Normal resting fibroblasts. 



cil.ep. Ciliated epithelium. viig.fbl. Migrating fibroblasts. 



deg.ov. Degenerating ovarian tissue. 7nsl.fbr. Muscle fibres. 



msl.nuc. Muscle nuclei. 



(N.B. The structure of the muscle tissue is merely indicated in the figures; 

 details of striation, etc., are omitted.) 



