3 8 4 
The Ohio Naturalist. 
[Vol. IX, No. 1, 
centrosomes in question and so it seemed to me to be quite 
unnecessary to look for them once more. Nevertheless, in order 
to make my assertion much firmer, I made, soon after his 
(Miyake’s) paper came into my hands, a special re-examination 
of my slides and could refind easily almost all stages of centro¬ 
somes figured in “Taf.” Ill, of my last paper.” 
Ikeno showed his slides to Dr. K. Toyama, a zoologist, who 
was able to see the centrosomes without difficulty. He thus 
comes to the conclusion that the bodies which he calls cen¬ 
trosomes are evidently distinct and constant structures in the 
antheridial cells of Marchantia. 
Escovez studying the same subject in 1907, makes the fol¬ 
lowing statement: “ Ces corpuscules du Marchantia polymorpha 
ne sont pas de vrais centrosomes, les porteurs de cils.” 
Schottlander reported the occurrence of centrosomes in 
Marchantia in 1892. He appears to have been the first to find 
these bodies in the Hepaticae and his methods seem to have 
given more reliable results than some of the later attempts in 
the same field. 
In 1900, Van Hook reported centrospheres with conspicuous 
radiations in vegetative cells of Marchantia. These centrosomes 
were observed in the young stalks of the archegoniophores. He 
says that “They seem undoubtedly to exert a great attractive 
force from the manner in which certain of the cell contents are 
drawn to them.” 
Miyake used the same methods as Ikeno. But different 
manipulation seems to have given different results. It is 
curious that with different methods I was able to obtain results 
similar to Ikeno’s. Why were Miyake and Escovez not able to 
manipulate the killing and staining processes so as to get the 
same appearances as Ikeno and myself? It is evident that in 
microtechnique the personal equation is large and similar meth¬ 
ods do not give the same results to all who use them. Therefore, 
it is useless to attempt to destroy positive evidence by negative 
results when one cannot produce the positive which others are 
able to obtain. 
After the appearance of Ikeno’s first paper, I prepared a large 
number of slides of the antheridiophores of Marchantia grown in 
the greenhouse. The material was killed in the weak chrom- 
acetic acid solution and stained on the slide in various ways. 
After much experimenting, I found that I could get the best 
results by staining with safranin and gentian violet and then 
restaining in Heidenhain’s haematoxylin. About one hundred 
of what appeared to be the best slides were selected for study. 
It was found, however, that in only about ten of these had the 
staining and clearing been done well enough to bring out clearly 
