280 DR J. M. MACFARLANE ON THE 



nuclear differentiation, and consist of an apparently simple protoplasmic mass. But the 

 power of movement, of digesting and assimilating food-particles, of retreating from 

 centres of disturbance or irritation, &c, would cause us to inquire whether the apparently 

 undifferentiated mass is not traversed by a fine protoplasmic reticulum of a neuromuscular 

 kind. Such is the view that many have held and still hold. 



But unicellular forms that show sexuality show also a nucleus, nucleolus, and 

 endonucleolus, the two last being often and carefully figured by Butschli, Huxley, and 

 others, while we consider their occurrence as universal in all cells of sexual plants and 

 animals. We have, however, already asserted our conviction that the nucleolus is the 

 important cell centre, and we have further proved by hybrid investigation that every 

 cell of an organism is hermaphrodite. Let us suppose, for attempted explanation, that 

 the nucleolus with its radiating chromatic threads is purely sexual, and is made up of the 

 fused chromatic constituents of male and female cells. Let us suppose further that the 

 nucleolar or sexual substance is gathered round a central differentiation or aggregation of 

 the protoplasmic reticulum, which might be the endonucleolus, and that it sends out 

 radiating chromatic processes along these threads which in part anastomose into a fine 

 chromatic layer — the nuclear membrane — so as to enclose in the interstices of the meshwork 

 system a quantity of nutritive protoplasm which is at once a bed for the nucleolus and a 

 feeder of it. Other radiating chromatic threads continued from the nucleolus and passing 

 beyond the nuclear membrane would ramify minutely through the protoplasm along the 

 threads of the reticulum, giving such appearances as we have traced in Spirogyra, 

 Masdevallia Veitchiana, Ornithogalum pyramidale, and Dioncea. 



The hypothesis would enable us to explain much that is at present involved and 

 obscure, while it would also enable us to dispense with the need for germ plasms. It 

 would permit us to entertain the possibility of a comparatively rapid intercommunication 

 of particles, and an even more rapid propagation of external stimuli, from cell to cell 

 accompanied by change in every molecule reached by these stimuli. The sum-total of 

 these would be expressed in the sex-cells, wdiich are the slowest to mature. 



We would thus view a plant as a group of connected hermaphrodite cells, 

 descended from a fertilized egg-cell, and bound together by a fine chromatic 

 ramification, the centre of which in each cell is the nucleolus. This chromatic system, 

 intimately in contact with the general protoplasm, would receive stimuli and nourishment 

 from it, while the combined action of these and other agents would tell not on one cell 

 or cell-group, but be shared to a greater or less extent by all. 



The above view does not compel us to suppose that the older cells in which the 

 nuclei are carried round in the protoplasmic current are thus connected, for these have 

 passed the stage of active division, and have their permanent life functions already 

 expressed. 



If we apply the above views to explain the frequent sterility of hybrids, a possible, or 

 we may venture to say, a probable hypothesis can be framed. If each reproductive cell 

 of an organism is specialised as an epitome of the individual which produces it (and in 



