The medullary protoplasm contains often chlorophyll, and also 
diatomin and starch or other amyloid substance. . . . The 
constitution of the cell-wall or cuticle from cellulose, as well as 
the presence of chlorophyll and diatomin, and the holophytic 
nutrition of many forms recently demonstrated by Bergh, has led 
to the suggestion that the dinoflagellata are to be regarded as 
plants, and allied to the Diatomacetc and Desmidiaceye. Physio- 
logical grounds of this kind have, however, as has been pointed 
out above, little importance in determining the affinities of 
Protozoa.” 
Another reason why the organism in question should not be 
regarded as injurious is that it does not appear to die and undergo 
decay. Some of those which I collected on 2nd April have been 
in a small bottle for ten days without change of water; and 
although the water swarms with bacteria and infusoria, they 
show no traces of decomposition ; they are, in fact, still alive, 
but motionless. After remaining in the bottle for about four 
days they settled down to the bottom, and ever since they have 
been undergoing certain changes , the necleus acquired a bright 
red colour, and afterwards divided into two nuclei ; after division 
they began to enlarge, and the rest of the contained protoplasm 
was gradually absorbed, and finally there were formed two large 
orange-coloured spores. This condition is evidently the well- 
known encysted state, which obtains in many of the lower plants 
and animals. When eneystment takes place, spores in most cases 
are provided with a thick cell -wall, and are endowed with a great 
power of resisting all kinds of injurious influences, so much so 
that many of these resting spores may be boiled, or kept in a dry 
state for a lengthened period, without destroying their vitality. 
Tf, in spite of such unfavourable conditions as mentioned above, 
they are capable of attaining to the encysted state, there is no 
reason to suppose that they would do otherwise when in their 
natural habitat. No doubt many of them may die, through 
injury, and make the water foul ; but still there is no trace of 
the dead bodies of the Peridinia on the surface of the mud, or 
ill the water where they are abundant. 
If the organism does not die in large numbers, and its composi- 
tion is not likely to be injurious, how lias it acted so injuriously 
on the littoral fanna? This is a difficult question to answer 
without direct experiment on the organisms affected. There 
are, however, several ways in which this may have been brought 
about, without supposing that the effects are the result of any 
poisonous qualities, or that they arise from the death and decom- 
position of the Peridinia themselves. The bivalve mollusca have 
evidently been the most affected, and their decomposition has had 
some influence in killing the limpets, periwinkles, and other 
animal life. The death of the bivalves may be attributed to 
several causes; the Peridinia may have been present in such 
