436 FRANK R. LILLIE 
Fig. 36 shows a case in which part of a sperm head has been left 
behind in the peripheral protoplasm at the point of entrance, and 
we have the completely rotated complex of cone, sperm nucleus 
and aster within. Another similar case is illustrated in fig. 37, 
and still other illustrations could be given. 
It will be noted that there are very considerable size differences 
in the sperm nuclei of figs. 35 to 37, and all of these are distinctly 
smaller than the normal comparable stage shown in fig. 11. But 
in these cases it is not necessary to rely on the distinctly smaller 
size as evidence of their partial nature, for we have the evidence 
of sperm remnants left at the point of penetration. In figs. 38 
and especially 39, however, we have cases in which the undeniably 
minute size of the sperm nuclei alone is sufficient evidence, taken 
in connection with the records of injury to the external sperm 
head by removal of the jelly illustrated in figs. 18 to 26, to prove 
that they have been derived from a mere fragment of an entire 
sperm head probably (in the case of fig. 39) not exceeding one- 
sixth to one-eighth of the bulk of the entire head, although the 
external part was entirely lost in this case. 
It is, perhaps, not necessary, but it may be well to emphasize 
the fact that the cases selected for illustration are all from com- 
plete series of sections, and that the neighboring sections were 
always consulted for possible parts of the sperm nucleus. The 
small size is not due to division by the microtome knife. The cases 
described are selections from a much greater number of records. 
It will be noted that if small fragments of a sperm head can 
produce aster formation in the egg, the possibility of polyspern y 
with parts of a single spermatozo6n is given. This condition, 
which I anticipated on theoretical grounds, was finally found 
and is illustrated in fig.40: There are two sperm nuclei, each with 
an aster, associated with a single cone. The small size of these 
nuclei marks them as partial, and their connection with a single 
cone as parts of a single spermatozoén. The only alternative 
explanation of this figure would be that two spermatozoa had 
become implanted so close together as to produce a single cone, 
and that they had received comparable injuries in the process of 
centrifuging. Against this explanation are the results of many 
