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Transactions of the Society. 
spermatids and “ nurse-cell.” The result of this connexion leads 
to the enlargement of the nucleolus of the “ nurse-cell,” and two 
nucleoli are often formed. This is shown in fig. 9. The “ sertoli ” 
cell (NC) is here growing out away from the trabecular wall of the 
ovatestis. The nucleus is elongated and has two spherical nucleoli. 
During fixation the nurse- cell appears to have contracted, and the 
result is that a number of fine protoplasmic filaments (PR) are seen 
attached to the developing heads of the sperm-cells. 
Other cases are met with in which the metamorphosing 
spermatids are attached to young oocytes. In such cases the 
nucleolus of the oocyte is either small or altogether absent. 
At fig. 8 is drawn a very curious condition. As has been 
described in a previous paper (3Jj), when the young oocyte grows 
out away from the wall of the ovatestis, neighbouring cells of- the 
germinal epithelium grow up around it and form a temporary 
follicle. Such an oocyte is shown in fig. 8. The nucleus of the 
oocyte (OC) has a large nucleolus (NL), spherical in shape, while 
that of the “nurse-cell” (NC) is elongated. The unique point 
about this is that developing spermatozoa (H) are also attached to 
the “nurse-cell.” It would seem, therefore, that although the 
“ nurse-cell ” has grown into its present position as the result of 
some stimulus from the growing oocyte, it also has a certain tactic 
(probably chemiotactic) influence upon the growing sperms. The 
actual formative processes going on in the sperm-cell have been 
described in the previous section of this paper. It is impossible to 
say what relationship exists between these processes and the 
function of the “ nurse-cell.” That there may be some nutritional 
relationship seems quite feasible ; there is also the problem as to 
whether such connexion between two cells, one predominantly 
anabolic, the other katabolic, has anything to do with neutralizing 
chemiotactic attraction between the male and female germ-cells 
of the same individual, and thus preventing self-fertilization. 
Very commonly “nurse-cells” with attached sperm-cells are 
found in the lumen of the reproductive organ. At fig. 10, PL IV, 
is shown a typical case. The nurse-cell is seen to be binucleate 
and in each part of the nucleus is a spherical nucleolus. Such a 
state of affairs may arise in one of two ways. Either the nucleus 
of the “ nurse-cell ” divides amitotically so as to exert a greater 
influence upon the metabolism of the cytoplasm, as Macklin 
observed in living cells (38), or the spermatids in the first place 
became grouped around two undifferentiated cells which subse- 
quently fused. Observations on living cells can alone settle this 
problem. Fig. 11 shows another cell which has functioned as a 
“ nurse-cell.” All but a few sperms (H) have broken away from 
it. The nucleus (N) of the “nurse-cell” is in a curious lobed 
condition, and it looks very much as though one nucleolus (NX) 
is being extruded into the cytoplasm. The double nucleolus of 
