Later Spermatogonial of Fasciola hepatica. 71 
account of their being grouped into masses of two, four and eight respectively, 
the two last spermatogonial divisions can be detected with a fair degree of 
certainty. 
No account of the events between the last spermatogonial anaphase 
and the meiotic prophase is given for Dicrocoeliwm, nor is the earlier 
spermatogonial telophase described at length. 
The oogenesis of Fasciola hepatica has been worked out by Adolf 
Schellenberg (4) who gives twelve and six as the somatic and reduced 
number of chromosomes respectively. Schubmann (5) gives eight as the 
somatic number. 
MATERIAL AND METHODS. 
The liver-flukes were obtained from infected sheep livers procured at 
a slaughter-house by Mr P. Jamieson. I should like to take this opportunity 
of thanking Professor Graham Kerr for the ever open hospitality offered in 
his laboratory to occasional visitors, and for the use of those requisites 
not possessed by the Notre Dame college laboratory. 
To Dr Agar also, who, just before leaving for the battle-front, very kindly 
read through the first draught of this manuscript, my thanks are offered. 
The eggs of the liver-flukes were incubated and then transferred to 
the fixative at regular intervals—the flukes were taken from the bile duct 
of the sheep, and placed either straight into the fixative or from warmed 
physiological salt solution into the fixative. Small portions containing gonad, 
as well as whole specimens, were then preserved. The fixatives employed 
were Flemming (strong solution), chloroform-acetic-sublimate, corrosive- 
acetic, corrosive alcohol, the fluids of Bouin, Zenker, Gilson-Petrunkewitsch 
and Hermann. The value of the various fixatives is discussed later. 
Sections from 7p to 10. thick were examined first—this thickness 
facilitating the examination of all nuclei in an uncut condition. But in these 
preparations the whole “group” (PJ. IV. fig. 22) was not always included 
in one section, and in order to be absolutely certain of its content it was 
necessary to investigate either the succeeding or the preceding section or both. 
To obviate this difficulty and to insure absolute accuracy the thickness of the 
later preparations was increased so as to include the whole group, whether of 
eight, sixteen or thirty-two cells, in one single section. This was effected by 
making the sections about 15u thick. The range was therefore from 7p to lou. 
The testis of Fasciola hepatica is too well known to require description. 
Examination of slides showed that the topographical relations of the cells 
and “groups” described for Dicrocoeliwm lanceatum are present also in this 
species. The spermatogonial nuclei are entirely confined to the periphery— 
the central lumen is filled with groups of eight, sixteen and thirty-two cells 
