‘ Heterotypical Reduction ; in Somatic Cells. 795 
every degree of incomplete separation of the groups of chromosomes. 
Here and there also occur tripolar divisions of peculiar shapes, often having 
a large mass of chromatin at one pole and a smaller mass at each of the 
others. In a few of these multipolar figures division has been complete, 
but in the majority strands of chromatin persist between the respective 
chromosome groups. The chromatin itself is granular, and when broken up 
into chromosomes shows the ‘ heterotypical 5 character to a marked degree. 
Groups of cells in rest are seen, of curious shape and oblique orientation, 
and containing nuclei of various size, lobed or amoeboid, and frequently 
with connexions remaining through the cell walls. Such groups of cells 
have evidently arisen through the imperfect multipolar divisions just de¬ 
scribed. Other cells contain nuclei of the familiar £ bridge ’ shape, and 
generally also a fragment of unfinished cell-plate. Others, again, have two 
nuclei at rest or going into division, and showing the duplication of equa¬ 
torial plates, diasters, and telophases already seen in Galtonia and the bean. 
These tetraploid cells have now increased in size. They occur throughout 
the root-tip, and rows of three or four are to be found near the growing 
point as well as further back. The round, deeply stained bodies noticed at 
the preceding fixation are extremely marked, in some cases almost obscuring 
the nucleus. Here and there are seen already, at some distance from the 
growing point, cells in which fragmentation of the nucleus itself has taken 
place. 
(3) After 45 hours of subsequent growth. 
After an interval of 45 hours the tissue has recovered its staining 
properties and presents a more normal appearance generally, the cell walls 
being better defined, and the cytoplasm less vacuolated. At the same time 
the number of structural abnormalities has if anything increased, these 
being the more evident from the great rapidity with which division is now 
taking place throughout the root-tip. Although the achromatic fibres arc 
more definite than at the preceding fixation, the division figures are still 
very irregular in character. The equatorial plates tend to be curved or 
split into a Y-shape, and multipolar division figures of great variety are to 
be seen. In some telophases a third small mass of chromatin is visible at 
one extremity of the cell-plate which divides two large masses. This has 
the appearance of having dropped out of the zone of activity during 
mitosis, rather than that of having arisen through tripolar division. Tetra¬ 
ploid cells are seen, containing two nuclei at all stages of rest and activity. 
Others show one equatorial plate or diaster of unusual size, which, on 
counting, is found to contain the tetraploid chromosome number, i. e. 28 
instead of the 14 normally found in the somatic tissue of the pea. The 
above cells, of greatly increased dimensions, are now found principally 
at a considerable distance from the growing point, and occur in rows of two 
