140 GILBERT (0. BOURNE. 
structure of a Metazoon, I think I am justified in pointing 
out that, if they are found to be of general application, our 
ideas on these subjects will have to undergo considerable 
modification. The ancestral metazoon will no longer be 
looked upon as a colonial protozoon, but rather as having 
the nature of a multinucleated infusorian, with a mouth 
leading into a central vacuolated tract of protoplasm. The 
continuity between the various cells of the adult—the connec- 
tions between the nerves and muscles and sensory epithelium, 
recelve an adequate morphological explanation, being due to 
a primitive continuity which has never been broken. In 
short, if these facts are generally applicable, development can 
no longer be looked upon as being essentially the formation of 
a number of units from a single primitive unit, and the 
co-ordination and modification of these units into a harmonious 
whole. But it must rather be regarded as a multiplication of 
nuclei and a specialisation of tracts and vacuoles in a con- 
tinuous mass of vacuolated protoplasm.” 
This is a temperate and lucid statement of a suggestion 
which is still worthy of serious consideration, the more so 
since it had been shown, but a short time previous, that 
protoplasmic continuity between the tissue-cells of plants is of 
very general occurrence, if not the rule. And, as a historical 
fact, the continuity of protoplasm was a phenomenon familiar 
to animal histologists long before it was proved for vegetable 
tissues; indeed there were authors who, before Mr. Walter 
Gardiner’s researches were published, were disposed to regard 
protoplasmic continuity as a characteristic of animal organisa- 
tion, discontinuity as a characteristic of vegetable organisa- 
tion. 
I have quoted at length because Mr. Sedgwick from being 
temperate has become intemperate, and from being lucid he 
has become obscure; so that, were I to deal only with his 
latest utterances, I should be quite at a loss to know what his 
maturer views might be. 
What follows, then, may be taken to be a not unfair state- 
ment of his position. That from the connection known to 
