650 DAVID HILT TENNEN'. 
whatever of the germ-cell until it has passed from the wall 
into the lumen. In a few instances I have noticed that a 
small cell had been cut off from the germ-cell as it was 
entering the cavity of the tube (fig. 15, a, and 16). 
Within the wall at this time there are also many small, 
rather transparent, yellowish bodies. These, after fixation 
with Flemming’s solution, become extremely black. I 
believe them to be fat droplets. 
Tur “ KEIMLAGER.”’ 
Besides the method of forming the germ-cells which is 
above described, another often occurs. This takes place 
towards the close of the first method. In this second method, 
instead of the scattered production of germ-cells, there is a 
localisation of production; a definite portion of the wall of 
the sporocyst, usually at one end of the tube, grows into the 
lumen as a blunt process (fig. 22), which functions as a 
special organ for the production of germs. In these pro- 
cesses the germ-cells, which are there differentiated, undergo 
their stages of segmentation and reach the condition of a 
germ-ball of considerable size, when they burst the tissue 
enclosing them and come to lie in the lumen of the tube 
where their further development takes place. 
This process has been described by Heckert (89, 1889) for 
Leucochloridium, by Looss (40, 1885) for Amphi- 
stomum subclavatum, and also by more recent investi- 
gators. 
The germ-cell, as it lies in the lumen of the tube, is a 
spherical body about 0°005 mm. in diameter, with a nucleus 
0:003 mm. in diameter. ‘The cytoplasm is dense, finely 
granular, and takes the stain easily. ‘The nucleus takes an 
even, darker stain, while its round nucleolus stains black. 
The first appearance of activity in the germ-cell itself is 
the cutting off of a small cell (fig. 15, 6). (As has been already 
noted, this may take place within the wall.) This cell differs 
in appearance from the much larger germ-cell in that its 
