differentiated, specialized, and arranged in a definite order, so it is possible or probable are the biaphors of a cell differentiated, specialized, and arranged in a definite order; and as all differences between multicellular organisms are due to differences in the differentiation, specialization, arrangement, and number of their cells, so all differences between cells are possibly or probably due to differences in the differentiation, specialization, arrangement, and number of their biaphors; and as higher multicellular organisms are more heterogeneous and complex as regards the nature and arrangement of their cells than lower multicellular organisms, so higher unicellular organisms are possibly or probably more heterogeneous and complex as regards the nature and arrangement of their biaphors than lower unicellular organisms; from which, if true, it follows as a corollary, that higher unicellular organisms are less capable of transmitting acquired variations than lower unicellular organisms, a deduction which is in accordance with the facts, so far as they have been observed; for while experiments have demonstrated that the microbes (in every case extremely low organisms) of several diseases are modifiable by cultivation in changed media, there is nothing to prove that higher unicellular organisms such as the amoeba are as easily modifiable. As regards the small-pox microbe, since it is so readily modifiable by removal to a different medium,—i.e. the calf's body,—it must, if there is any truth in this hypothesis, be a very low organism—low as regards the number, arrangement, differentiation, and specialization of its biaphors—a view which is borne out by the fact, that it is so minute that it has never been seen, notwithstanding the exceptional facilities that the limpid vaccine lymph affords for microscopic investigation; possibly it is so minute as to be quite beyond the powers of devisable microscopes, in which case it will never be discovered.
