68 
PROFESSOR E. RAT LANKESTER. 
that drawn in fig. 24. This is by no means the largest colony 
which I observed, and in this specimen the chlorophyll-cor- 
puscles were all in an active state of tetraschistic division. I 
decolourized this colony by the introduction of alcohol between 
the glass slide and cover, whilst under observation, and, 
subsequently stained the organism by picro-carmine intro- 
duced in the same way. All the larger chlorophyll-corpuscles 
then exhibited the structure shown in fig. 25. Whilst the 
smaller corpuscles (which presumably had only recently been 
formed by tetraschistic division) exhibited the structure shown 
in fig. 26. The shaded parts in these two figures correspond 
to a decided but not very strong staining effected by the 
picro-carmine. 
The size of the chlorophyll-corpuscles in these vegetative 
groups varies. They are never so large as in the Actinophryd 
phase, but may attain a diameter of go'o pth of an inch, and 
may be, in such exceedingly active specimens as fig. 24, as low 
as T 6- ooo th of an inch. 
It appears that there is no constant size which the chloro- 
phyll-corpuscle must attain before division, but that this 
varies in different specimens according to the individual activity 
of the vegetative process in each group. Apparently, where 
the protoplasm is abundant and is taking much nourishment, 
the chlorophyll-corpuscles multiply rapidly and enter upon the 
fission-process at an earlier period of growth — that is to say, 
when they have attained a less diameter — than is the case 
where the protoplasm is less abundant. It would almost seem 
as though, receding from the Actinophryd-phase, the chloro- 
phyll-corpuscles divide successively at earlier and earlier stages 
of their growth, until a maximum of associated corpuscles and 
a minimum of their individual size is attained. It seems not 
improbable that this excessive growth and subdivision of the 
chlorophyll-corpuscles is favoured by abundant nutrition. A 
time arrives when the conditions for nutrition are less favour- 
able. The individual chlorophyll-corpuscles then grow instead 
of dividing and each becomes detached, together with some of 
the protoplasm, from association with its neighbours. Such a 
