^IrunlacKTS^^ jRoyaZ Microscopical Society, 273 
space, as if the rest of the cell-contents had retreated towards the 
circumference by a sort of repulsion. It is quite possible that this 
space is filled with fluid squeezed out of the interstices between the 
granules by their closer approximation when forming the nucleus. 
These cells vary in size from 0-013"^™ to O'OIS^^'", and the 
nucleus from 0 • 008"^"^ to 0 • 010"™. (Fig. 8c) Besides these larger 
cells, there are also smaller ones, granular like the former, appearing 
to be sohd, often developing a granular nucleus, but sometimes not 
showing one, even after having remained some hours on the shde. 
They range in diameter from 0 ' 008""" to 0 ' 010, being of the same 
size as the nuclei of the larger cells. It was not evident that they 
had been set free by the breaking up of the latter ; but rather 
they gave me the impression that they were a younger form becom- 
ing transformed into them by a process of continuous growth. 
These are not the only form of cell to be found at this part of 
the testicular tube. There are others (Fig. ^d) whose nucleus is 
round and perfectly smooth. Some of them are as large as the first- 
mentioned cells: others are larger than the nuclei of the same. 
Thus they measure from 0*011"™ to about 0-015™"\ It will be 
observed, on looking at the figure, that the nucleus varies in posi- 
tion, being nearly in the centre in one cell ; in another just 
touching the margin; and in the two others even projecting 
beyond. (Fig. 8 e) Occasionally there occur cells with an elongated 
rod-like nucleus. These resemble the last in every other respect 
but shape of the nucleus. Sometimes the latter occurs double 
(Fig. 8 /), which seems to take place by the single one doubling 
over and separating in the middle. 
Some of the cells (Fig. 8^) appear to be undergoing division. 
They have two granular nuclei, and are rather larger than the 
former, measuring 0 • 021™'" in diameter. 
In one case (Fig. amoeboid movements of small extent, but 
very distinct, were seen, a protuberance appearing suddenly first, on 
one side and then on the other; the cell afterwards remaining 
stationary for some time. This is the only instance of these move- 
ments which occurred during my investigations. It was first 
noticed in sperm-cells by St. George de la Valette.* The nuclei 
in these are larger than in the former cells, occupying nearly 
the whole extent. I did not expressly look for this movement, or 
perhaps I should have met with it oftener. 
These difierent kinds of cells vary greatly in number in different 
animals. In one specimen nearly all would have granular nuclei ; 
in another, the smooth ones would greatly predominate ; and again, 
in another, nearly all the cells would have rodlike nuclei. I have 
found the blood of the animal to be the best medium in which to 
examine these cells. It is true there are blood-corpuscles present in 
* Max Schultze's 'Archiv,' Bd. 1, Heft 1. 
