1906] LEWIS—DEVELOPMENT OF RICCIA 127 
appears there. On the other hand centrosome-like bodies appear 
in the cells of the older antheridia at the time of nuclear division. 
There can be no doubt that these are distinct bodies, and they cannot 
possibly be interpreted as accidental granules in that position. In 
Some of my preparations hundreds of cells showing them are found 
on a single slide, and they are so distinct that the preparation could 
easily be used for class demonstration. These bodies appear in 
the cells of the antheridium in early stages of its development. I 
have been unable to determine whether they appear in the earliest 
cell divisions but they appear in the antheridia which consist of only 
a few cells. They are not permanent, but disappear and arise anew 
with each division. 
IKENO regarded it as highly probable (though unable to state this 
positively) that in Marchantia these bodies were of nuclear origin. 
He figures a small spherical body inside the nuclear membrane, 
which in a later stage is found outside the membrane. This body 
then divides into two, which arrange themselves on opposite sides of 
the nucleus. If the bodies have their origin as one, which later 
divides as described, they act as do the ceritrosomes which have 
been described for other plants. 
In Riccia natans, nothing has been observed to indicate that the 
body is of nuclear origin, except that it stains in much the same 
Way as the mass of chromatin in the nucleus. In some of my pre- 
parations a single body has been observed near the nuclear membrane 
(fig. 53). These bodies have never seemed so distinct as the ones 
Which appear at the opposite ends of the nucleus and in the poles 
of the spindle. There is a dark central part, surrounded by a mass 
of cytoplasm which is more or less irregular but does not give the 
appearance of distinct radiations such as are described i in the centro- 
spheres of certain plants. 
When these single bodies were discovered, a careful search was 
made of the same preparations and of others in which the two bodies 
were on the opposite sides of the nucleus, in order to discover if 
possible the intermediate stages which it would seem should appear 
in such preparations. In cases in which two bodies have been 
observed, they have always been on opposite sides of the nucleus, 
©r so nearly opposite that -the spindle developing between them 
