IF. D. Lang — Bernard's Biological Theories of Fossils. 551 



the ' cytoplasmic ' matrix. The unit of this arrangement, then, is 

 a single chromidium with radiating linin strands ; and a homo- 

 geneous aggregate of such units is the linin-chromatin, or, as Bernard 

 calls it, the ' protomitomic ', network. 



Such a network is the condition of cells that have no apparent 

 nucleus, or of those which, in terms of the cell-theoiy, the nucleus is 

 fragmented. And the reason why this structure has not hitherto 

 been postulated as fundamental in all protoplasmic bodies, is that 

 in general circumstances the linin is invisible by our present means 

 of vision; but when chromidia stream along the filaments, owing to 

 their staining properties, they cause the filaments to appear. Then 

 they have been observed, for instance, in a nucleus dividing by mitosis ; 

 and variously accounted for. For the linin strands are the paths of 

 the chromidia which in their turn are the storehouses of energy. 

 Where work is done, and in proportion as more or less energy is 

 required, thither and in greater or less quantity stream the chromidia 

 along the linin strands. The strands are essentially contractile as 

 well as capable of transmitting stimuli from the exterior to other 

 portions of the network, and it is specialized bundles of linin strands 

 that ultimately form nervous and muscular tissue. It is along them, 

 too, that waste matters tz'avel outwards and are deposited either 

 around the strands (or bundles of them) or at their tips, forming an 

 endo- or exoskeleton. 



The cell is derived from the primitive linin-chromatin network by 

 the massing together of the nodes and the consequent tangling of the 

 linin threads. The massed nodes constitute the nucleus, and the 

 linin filaments, though tangled, liave as a whole a radial arrangement, 

 and their ends, projecting from the 'cytoplasmic' matrix, either 

 singly or in strands, appear as cilia. ^ 



Homogeneous aggregates of cells form three-dimensioned networks 

 very similar to the primitive protomitomic network, but on a larger 

 scale and essentially of a more complex structure. Examples of such 

 are Volvox (fig. 21, p. 107), the larval sponge (fig. 14, p. 91), and 

 the tissue of the vertebrate retina (fig. 33, p. 218). 



Such, in bald outline, is Bernard's protomitomic theory, if I have 

 rightly understood it. The evidence adduced in its support is mainly 

 that of structures such as the vertebrate retina and the nuclear 

 spindle and centrosomes of karyokinesis, difficult of explanation bj- 

 the cell-theory, but easily accounted for if Bernard's point of view is 

 accepted. Moreover, his view reconciles different and apparently 

 exclusive theories of protoplasmic structure, such as the ' foam- 

 structure ' theory of Biitschli, founded on the globular appearance of 

 the albuminous matrix between the protomitomic meshes, and the 

 ' biophor ' theory of Altmann, the granules of which are the chromidia! 

 nodes. ^ The protomitomic theory does not annihilate the cell-theory, 



^ Bernard's explanation of the nuclear wall as a felted tangle of linin threads 

 is not very convincing, for the tangling would, presumably, be greatest at the 

 nucleus and gradually less towards the periphery of the cell. 



^ The reader must refer to the work itself to gain a proper idea of the number 

 of otherwise inexplicable phenomena in morphology that can be readily 

 construed in terms of the protomitomic theory. 



