The Somatic Nuclei of Certain Cestodes. 
153 
definite outlines are lacking. They consist rather of irregulär masses 
of darkly staining granules, which are themselves irregulär in shape, 
size and density, and which group themselves in a general way about 
a central, unstained area, which may or may not contain a central granule 
or »nucleolus«. No definite membrane is here present. The granules 
are frequently massed eccentrically to one or the other side of the nu- 
cleus, while occasionally they are scattered promiscuously thru it. 
Evident de novo formation in cytogenic masses is difficult to find 
but a few probable cases have come to my notice. In one of these I find 
in a cytogenic inass in the parenchvma of the neck region of the worin 
an incomplete membrane surrounding a few fine granules. I have exam- 
ined both adjacent sections and find no other nuclei from which thiä 
could in any probability have arisen. 
In the developing genital ducts I find similar conditions to those 
described in other species. The anlage of the duct here consists of a 
syncitium of densely packed nuclei varying in shape, size, amount of 
chromatin content and presence or absence of nuclear membranes. These 
differences, while not conclusive evidence of de novo formation, point 
I believe in that direction. 
In some cases in the sub-cuticula the cell bodies are not delinitely 
outlined, the nuclei lying free in the fibrillär protoplasmic mass. In 
others, tho these are infrequent, the nuclei possess no definite »nucleoli«, 
but instead a reticulum with small indefinite scattered granules. Variat- 
ions in staining density of different nuclei occur. 
A careful examination of several nuclei shows an absence of any 
complete nuclear membrane. It is rather the peripheral part of the nu- 
clear net-work containing numerous openings. 
There is some evidence of the amitotic multiplication of nuclei in 
this worm, but I have found not a single case of mitosis tho I have exain- 
ined 3300 nuclei 1 ). 
As an example of the Rhynchobothriidae I have chosen 
Rhynchobothrium bulbifer. 
(Fig. 13.) 
In this material I find some evidence of nuclear multiplication by 
direct division of pre-existent nuclei, a few nuclei strongly suggesting 
this process. 
In the developing genital duct of one worm I find a closely packed 
*) See footnote 1), p. 145. 
