Page:Popular Science Monthly Volume 26.djvu/838

818 similar condition, since they probably penetrate the cells as minute fibrils.

C. Heitzmann, a skilled microscopist, now of New York, has long maintained, and has recently reiterated, a theory which declares that this fibrillar extension is not confined to epithelial and ganglion cells, but is common to all the cells of the body, and that intimate interconnections between all the cells and tissues are thus made. Even the bony structure he declares to be everywhere permeated by tine channels, in which run fibrils of protoplasm, connecting the granular and nuclear masses throughout the whole substance. He, indeed, denies the existence of separate cells, and claims that the body is simply a vast reticulum, with nuclear masses as nodes of the network. Instead of being composed of numerous separate amœboid cells, it is a single complex amœba.

This bioplasson theory is not accepted by microscopists generally, and it certainly goes too far in denying the existence of distinct cell structures. It may be possible that it indicates a final stage in the process of cell-evolution. Distinct isolated cells undoubtedly exist in the blood and lymph fluids of the body. But in the more solid tissues this isolation is, in some cases at least, replaced by an interconnection of cells through the medium of inosculating fibrils. And it is quite possible that this fibrillar extension becomes so declared in extreme cases as to produce the appearances described by Heitzmann. The basis or ground-substance of the outer cell of osseous tissue may be converted, by deposition of lime-salts, into bony matter, through which the fibrils extend from the nuclei in open channels. If this theory be correct, the original cell becomes a nuclear center of active protoplasm and an outer region whose ground-substance is converted into bone, while its protoplasmic fibrils extend until they join similar fibrils of other cells, thus converting the whole mass into a living network whose interspaces are occupied with bone.

In other tissues a similar condition may exist, the bony matter of the osseous ground-substance being represented by other inactive material proper to the tissue. Perhaps every phase of differentiation exists, from the completely isolated corpuscles of the liquid tissues to the complete and extended reticular structure described as existing in bone.

This theory naturally leads to some probable speculative views. If, as seems evident, the nerve-fibers originate in such extensions of the intercellular network, possibly the fibrils of individual cells have a conductive or nerve function, as also the contractile or muscle function which some writers ascribe to them. Their extension from cell to cell would indicate nerve communication, and it may be that the undoubted nerve and muscle function of many low animals, in which no nerves and muscles have been discovered, may be due to these interlacing fibrils. And the widely extended nerve-system of the higher