No. 466.] STUDIES ON PLANT CELL.— VIII. 713 
But the manifestations of kinoplasm during nuclear division 
and also in relation to cilia-bearing surfaces are exceedingly 
various and it is among these structures that our ignorance of 
relationships and modes of origin is deepest. These kinoplasmic 
structures have been described in various connections through- 
out this series of papers and especially in Sections I, II, and 
III, and need not be treated here. But the point which should 
be emphasized in this connection is the necessity of the close 
study of their simplest expressions in the lower regions of the 
thallophytes.* The most varied forms of kinoplasm are in the 
thallophytes where asters, centrospheres, and centrosomes ob- 
tain and: where ciliated cells, presumably with blepharoplasts, 
may occupy long periods of the life history. It is here that we 
must search for information that will bring order out of the con- 
fusion of our present accounts and insufficiency of knowledge. 
The most vital problems relating to kinoplasm concern the ori- 
gin and the events of the simplest types of mitotic phenomena 
and the formation of cilia. We have a fairly clear understand- 
ing of the general features of mitosis in the groups above the 
thallophytes and their relation to the lower types and these will 
be briefly treated in the following portion of this section under 
the head: *Some Apparent Tendencies in the Evolution of 
Mitotic Phenomena." But the events of mitosis among the 
thallophytes are exceedingly various and difficult to understand 
and nothing is known of their origin or relation to the simpler 
conditions which must be present in the lowest regions of the 
Chlorophyceze and in the Cyanophycez. 
Trophoplasm comprises all of the cytoplasm included within 
the plasma membranes. While this region does not give rise to 
such highly differentiated cell organs as the kinoplasm, never- 
theless some remarkably interesting structures are developed. 
Coenocentra and Physodes are specialized structures of exceed- 
ing interest and our ignorance of the latter is truly remarkable. 
Nematocysts if trophoplasmic offer another attractive subject for 
investigation. In a sense, chromatophores and plastids may be 
considered trophoplasmic but their high grade of specialization 
and fixity as cell organs gives them a certain independence of 
other structures in the cell. Respecting the structure of the 
