148 GILBERT C. BOURNE. 
interpret to our minds one of the most universal of organic 
phenomena, viz. the splitting up of protoplasmic masses during 
growth into a number of more or less distinct corpuscles. 
It will not be out of place if I quote here a passage from 
von Sach’s ‘ Vorlesungen uber Pflanzenphysiologie’ (English 
edition, translated by H. Marshall Ward, 1887, p. 73). ‘To 
many the cell is always an independent living being, which 
sometimes exists for itself alone, and sometimes becomes 
‘joined with others °—millions of its like, in order to form a 
cell colony, or as Hackel has named it for the plant parti- 
cularly, a cell republic. ‘To others again, to whom the author 
of this book also belongs, cell-formation is a phenomenon very 
general, it is true, in organic life, but still only of secondary 
significance; at all events it is merely one of the numerous 
expressions of the formative forces which reside in all matter, 
in the highest degree, however, in organic substance.” 
That this is a great limitation of the cell theory, both as 
propounded by its authors and as held by many zoologists, is 
not to be denied; and Mr. Sedgwick might well be content 
if some such statement were made the established doctrine 
as regards cells. It appears to me that some such limited 
statement is necessary if we are to have any proposition 
universally applicable to organic structure; but with this 
reservation, that I cannot regard as of secondary significance 
that which all experience shows to be the expression par 
excellence of organic growth. 
In admitting this much, a large part of Mr. Sedgwick’s 
demand is conceded, for it is not to be denied that the cell 
theory has been very differently and much more dogmatically 
stated by quite recent authors. 
We have, for instance, Dr. Oscar Hertwig’s recent work, 
‘Die Zelle und die Gewebe.’ He begins dogmatically enough 
by saying, ‘‘ Thiere und Pflanzen, so verschiedenartig in ihren 
dausseren Erscheinung, stimmen in den Grundlagen ihres ana- 
tomischen Aufbaues iiberein; denn beide sind aus gleich- 
artigen, meist nur mikroskopisch wahrnehmbaren Elemen- 
tareinheiten zusammengesetzt. ... Denn die Zellen, in 
