156 GILBERT ©. BOURNE. 
manifestation of growth, and Mr. Sedgwick may contend that 
his views are thereby conceded, and that the ancestral meta- 
zoon may, on this aspect, be considered as “‘ a multinucleate 
infusorian with a mouth leading into a central vacuolated mass 
of protoplasm.” There may be truth in the contention, yet 
none the less we may hold fast to the concept of a cell, as I shall 
attempt to show further on. And it may be observed in pass- 
ing that Mr. Walter Gardiner, in describing and emphasising 
the continuity of protoplasm in plants, expressly stated “ that 
the presence of minute perforations of the cell-wall need not 
lead to any modification of our general ideas as to the mechan- 
ism of the cell,” a proposition which most reflective persons 
will be cordially inclined to agree with. For this much is 
certain, that the formation of cells is not merely the expression 
of one out of many formative processes which reside in organic 
matter, but is the formative process, par excellence, which 
obtains both in animal and vegetable tissues. 
Thus far I have endeavoured to show that the independent- 
- life-unit theory has not held the minds of zoologists in an iron 
bondage, much less the minds of biologists, for, when reference 
is made to biologists, botanists must be taken into equal 
account with zoologists. 
It is, however, arguable that, whatever botanists have thought, 
zoologists have not followed their example, but have publicly 
maintained a complete adherence to the independent-life-unit 
theory in its most limited form, whatever reservations they 
may privately have made in their own minds. 
But it may be doubted whether the argument holds good. 
I have already shown that passages which seem to state most 
dogmatically that cells are separate individuals, prove on 
examination to be nothing more than illustrations ; and it is 
to be remembered that ideas founded on botanical evidence 
must always be reflected ou the minds of zoologists, and one 
may certainly say that conceptions of animal structure have 
of late years been considerably modified by the light thrown 
upon organic structure in general by botanical investigation. 
Some zoologists may possibly have given too little attention to 
