426 R. T. Young 
which is probably a chiomatin granule, a condition described and figured 
by Child in Moniezia. 
In some instances however I have traced the sperm for a considerable 
distance into the cytophore, wliere it terminated, either free, or in a granule, 
which I interpret as a fragment of clironiatin derived from the degenerate 
spermatocyte skeins. Such a condition is shown in figs. 18, 19 and 27, 
which are camera drawings of fresh material from Rhyncobothrium. In 
a few cases also I have seen very delicate sperms lying in cytophores of 
Taenia or Dipylidium. Owing to the method of preparation however it 
is impossible to say that these ai'e not the tips of broken sperms wliich 
have beeil pushed into the cytophores by the pressure of the cover glass. 
In fixed material I frequently find developing sperms lying in the cyto- 
phore, but this may be an artefact since such conditions are rare in fresh 
material. This is illustrated in figs. 5 and 7. 
In most cases these developing sperms appear to aiise either from 
skein fragments in the cytophore or from chromidial extrusions of the 
cytophore nuclei, but in a few instances these latter appear to be bodily 
transformed into the sperms. In this case the cytophore nuclei are replaced 
by rather hazy indefinite elongate masses, staining like chi-omatin, and 
passing by various gradations into the definite, sharply outlined sperms 
(figs. 5 and 7). I have noted a similar difference in development in my 
previous paper (1. c. pp. 379—380), where I described some of the devel- 
oping sperms as hollow, and others as solid structures, both however 
ultimately forming the same adult type. 
In living material I have no clear evidence of the dh’ect participation 
of the nucleus in sperm formation, tho I have seen a few cases which 
suggest this.* Thus in fig. 32, which is a camera drawing from fresh material 
of Rhyncobothrium, a sperm may be seen attached to a nucleus, with a 
slight enlargement of the sperm at its point of attachnient to the latter, 
thus suggesting the structure of the typical flagellate sperm, with head, 
middle piece and tail. Seither here however, nor elsewhere in living 
material, is there evidence of the elongation of a nucleus to form a sperm 
head. On the contrary there is considerable evidence against such an 
assumption. 
This is first, the occasional termination of spenns free, or attached 
to granules in the cytophore, but unconnected to any nucleus, as already 
described. Second, their occasional attachnient to protoplasmic masses 
lacking nuclei, as shown in fig. 25. That such masses are actually 
and not apparently anucleate is proven by staining with methyl green, 
which clearly differentiates the nuclei in adjoining cells or cytophores. 
