Frenzel’s Mesozoon Salinella. 467 
he says (Biol. Centralbl. Joc. ect. p. 577; Ann. & Mag. Nat. 
Hist. oc. cit. p. 80) :—“In the systematic arrangement of 
the group (¢. e. the Protozoa) we are even obliged, hard 
though it will be for every modern zoologist, to allow our- 
selves to be swayed by physiological considerations, since 
here the purely morphological and embryological foundations 
are insufficient.” In cases in which “ unfortunately far too 
little attention is paid” to a “by no means unimportant 
difference . . . . perhaps in consequence of the fact that it 
arises in the first place from physiological conditions only,” 
this does not occur because it would be hard for a modern 
zoologist to take physiological considerations into account, 
but because there are unfortunately still far too many zoolo- 
gists who are one-sided in their views, 7. e. not modern. It 
appears to me that precisely the perception that differences of 
a purely physiological nature exist between organisms, espe- . 
cially unicellular ones, which are not to be distinguished 
morphologically (¢. e. anatomically and embryologically), is 
one of the most important acquisitions in biology; for it 
teaches us that the most essential differences—at least in my 
opinion—between organisms are independent of the decree of 
development which their organization has attained ; and that 
protoplasm, or, better, Protoblasts—for independent proto- 
plasm, without forming any kind of Protoblast or living 
being (Lebewesen), has no existence at all—is subject to 
material differences even in the non-organized condition. 
Indeed, we must even arrive at the conclusion—in a manner 
which JI will perhaps indicate more closely upon another 
occasion—that in the non-organized condition there already 
were AT LEAST as many original kinds of Protoblasts as there 
are to-day REALLY INDEPENDENT forms of living beings, or, 
we might say, QUALITIES OF LIFE; probably, however, there 
were many more. It may be that new qualities of life, in 
spite of the diversity of gradually developing forms of life, 
did not subsequently come into existence at all; for new and 
different FORMS OF LIFE may arise by gradual change of shape 
from apparently similar QUALITIES OF LIFE, the difference 
between which, though present from the beginning, does not 
become perceptible until a higher grade of development is 
reached. Yet it is probable that the qualities of life which 
were originally present cannot all have sustained the struggle 
for existence until now. 
More or less visible gulfs between the various forms of life 
are and must be present, therefore, if we would in any way 
identify the idea of difference with that of a gulf. The 
apparent size of such a gulf may in the first netics depend 
35 
¢ 
