44 
largest deutoplasm-spheres, vacuoles or 
other metaplasmic deposits, the alveolar 
spheres of Arbacia or Toxopneustes and those 
occurring in tissue-cells; and probably all 
are, in the sense indicated above, to be 
classed among the relatively passive or 
metaplasmic material. 
How generally the alveolar, reticular or 
fibrillar formations may occur is a matter 
still to be determined by observation. It 
is probable that the alveolar structure will 
be found to be of more general occurrence 
than has been supposed; and, judging by 
the appearance observed in echinoderm 
and other eggs, and in coagulated albumen 
and other structureless proteids, I suspect 
that some cases of so-called ‘reticular’ 
formations will be found to arise through 
the more or less imperfect fixation of the 
alveolar, leading to the coagulation, con- 
traction and breaking down of the alveolar 
walls,* though I do not for a moment mean 
to imply that such is the case with all re- 
ticula. 
What light, if any, do the foregoing gen- 
eral conclusions throw on the theoretical 
views outlined at the beginning of this lec- 
ture? The answer must be: None that is 
clear and satisfactory, for the background 
of all the phenomena appears to lie in the 
invisible organization of a substance which 
seems to the eye homogeneous. Yet there 
is, I think, much in these conclusions to 
suggest, and nothing to contradict, the hy- 
pothesis that the ‘homogeneous’ or ‘ con- 
tinuous’ substance may be composed of ultra- 
microscopical bodies, by the growth and 
differentiation of which the visible elements 
arise, and which differ among themselves 
chemically and otherwise, as is the case 
with the larger masses to which they give 
rise. I will not enter upon a discussion of 
the question whether these bodies are 
*It may be well to point out that Rhumbler has 
produced true fibrillar and reticular formations in 
coagulated artificial gelatine-emulsions. 
SCIENCE. 
[N.S. Vou. X. No. 237- 
merely molecules, more or less complex, or 
groups of molecules forming protoplasmic 
units or micelle, but will only make three 
suggestions: First, if such units exist, they 
cannot be identified with the visible gran- 
ules or ‘bioblasts’ of Altmann, but are’ 
bodies far smaller. Second, if there be any 
truth in what has been said above regard- 
ing the localization of ‘living’ matter in 
the cell, such protoplasmic units, if they 
exist, cannot properly be called ‘ biophores,’ 
since life is a manifestation of the system 
which they form, and not of the individual 
units. The corpuscular, or micellar theory 
of protoplasm, as an hypothesis of morpho- 
logical organization, should not be con- 
founded with the physiological theory that 
biophores or pangens are ‘elementary liv- 
ing units.’ Third, by ascribing to these 
hypothetical units the power of growth and 
division, in accordance with the pangen 
theory, we are enabled to get a certain 
amount of light upon some of the most 
puzzling questions of cytology, such, for 
example, as the ultimate nature and origin of 
dividing cell-organs like the nucleus or the 
plastids, and especially such a contradiction 
as that presented by the centrosome, which 
may apparently arise either de novo or by 
division of a preexisting body of the same 
kind. As De Vries and Wiesner have so 
suggestively urged, the power of division 
on which the law of genetic continuity rests 
and which is manifested by morphological 
aggregates of so many different degrees, 
may have its root in a like power of the 
primary units at the bottom of the series, 
out of which all the higher members are 
built. But while giving due weight to this 
suggestive hypothesis, we may question 
whether its acceptance does not introduce 
as many new special difficulties as those 
which it sets aside; while we must admit 
that it leaves untouched the fundamental 
problem of division. The solution of this 
problem may perhaps have to be sought in 
