1910-11.] Development of Germ Cells in Mammalian Ovary. 1 75 
4. Large cells — giant or resting cells — are found by me in the reticular 
stage of the primary oocyte. 
5. “ Pfltiger’s tubules” are columns or clusters of cells derived from the 
oogonia, separated off by means of the stroma cells. 
6. The growth of the stroma and germ cells is mutually correlated 
throughout the development of the ovary. 
7. The follicle cells — which form the cells of the stratum granulosum — 
are derived from the oogonia, and not from the stroma cells. The latter 
are only supporting and vascular. 
8. The reserve cells (oogonia and regressive oocytes scattered throughout 
the ovarian tissue) may function as follicle or as intersitial cells ; they may 
become absorbed as pabulum for the developing oocyte. 
9. The primary oocytes undergo transformations in their early matura- 
tion stages, which correspond to the prophase of the heterotypical divisions 
occurring in plants and animals. 
10. The stage of synapsis I find is the most prolonged and of most im- 
portance. This agrees with Berghs and others. The chromatin filaments 
undergo a pseudo-reduction during this stage, and they undergo apparent 
longitudinal division in the stage following the formation of the thick 
spireme. 
11. The nucleolus persists during all the stages of transition of the 
nucleus, although its staining capacity may vary. 
12. I have found no evidence in the medullary cords of the presence of 
cells which may lead to the formation of primary oocytes. The glandular 
structures in the hilum are the remains of the Wolffian and rete tubules. 
I gratefully acknowledge much kind help and encouragement in the 
carrying out of this research from Professor Noel Paton ; and also Dr G. 
Herbert Clark, who kindly procured specimens for the work. I am in- 
debted for the photographs to Mr Richard Muir, Edinburgh University. 
LITERATURE. 
(1) Balfour, F, M., Quart. Journ. of Microscoy. Soc ., vol. xviii., 1878: “On 
the Structure and Development of the Vertebrate Ovary.” 
(2) Berghs, Jules, La Cellule, t. xxii., 1905: “La formation des chromosomes 
heterotypiques dans la sporogenese vegetale.” 
(3) Bolles Lee, A., La Celiule, t. xiii., “ Les emeses spermatogenetiques chez 
l’Helix pomatia.” 
(4) Bryce, T. H., Quain’s Elements of Anatomy , vol. of Embryology, 1908. 
Quart. Journ. of Micros . Soc., vol. xxiv., 1903 : “ Maturation of the Ovum in 
Echinus esculentus.” 
