of Edinburgh, Session 1885-86. 
803 
4. On the Anatomy of Suberites domuncula. By J. Arthur 
Thomson, M.A. Communicated by Patrick Geddes, 
Esq. 
5. History and Theory of Spermatogenesis. By Patrick 
Geddes and J. Arthur Thomson. (Plate XXIX.) 
The development of spermatozoa has been for the last twenty 
years the subject of prolonged research and controversy, which 
cannot yet he said to have resulted in satisfactory solution of the 
involved problems. In view of the intrinsic difficulties of the 
subject, and the discrepant results and nomenclature of different 
authorities, it is the object of the present paper to recapitulate the 
history of investigation, to collate the results and the nomenclature, 
and to propose a theory which will explain and rationalise the maze 
of apparently conflicting observations. 
§ 1. History . — The modern period of investigation, despite a few 
researches by Wagner, Yon Siehold, and others, practically opens 
with Kolliker’s fundamental observation* (1841), that the head of 
each spermatozoon arose from the nucleus of a seminal cell (Samen- 
bildungzelle). 
In 1844 Meckel described, in Helix, how the cell destined to 
become spermatozoa arose superficially from a mother-cell, in the 
epithelium of the germ follicle. According to Kolliker, however, 
the central body round which the immature sperms were grouped was 
no cell, but only the residue of the mother-cell within which the 
sperm cells had arisen endogenously. The research of Ankermann* 
(1854) also deserves mention, for his derivation of each spermatozoon 
from a distinct cell. 
The account of spermatogenesis became somewhat more complex 
when Kolliker described, in 1856, two kinds of cells lining the 
tubules — (a) outer cells with large nuclei and nucleoli, and under- 
going rapid multiplication; (b) inner cells, becoming differentiated 
into seminal cells, which formed in some cases cysts, and from 
whose nuclei the spermatozoa were formed. Henle also dis- 
tinguished two kinds of round cells (a) with granular, and ( b ) with 
* For papers referred to see Bibliography, in which the authors’ names 
are arranged alphabetically. 
