204 Mr J. M. Macfarlane on the 



ing till three or four times the diameter of tlie nucleus, 

 most of the curled-up threads could be seen adhering. 

 This experiment was so novel and magical, if I be allowed 

 the expression, that I repeated it frequently, and in the 

 presence of various gentlemen who were quite satisfied with 

 it ; and subsequent repeated trials have given unvarying 

 results both on isolated nuclei and aggregate masses. Any- 

 one can verify the facts for himself, by attending merely to 

 the points mentioned. 



The structure, thus demonstrated in so positive a manner, 

 clearly corresponds to the nuclear membrane of animal 

 cells as described by Klein * and others. Now Klein has 

 asserted that in cells from the stomach of the newt the 

 " nuclear membrane is composed of an outer thicker por- 

 tion, which is the limiting membrane proper, and, closely 

 connected with it, of an inner — more or less incomplete, 

 probably . because reticular— delicate layer, which is, pro- 

 perly speakings a peripheral condensation of the intranuclear 

 network." The cells of the alga, now under consideration, 

 are identical in their anatomical details, for after the outer 

 nuclear membrane has detached itself and increased con- 

 siderably, one can plainly see a clear but rather irregular 

 band enveloping the nucleus. A matter, however, rather 

 difficult of solution now suggests itself. Why, on rupture 

 of the radiating threads, does the outer membrane detach 

 itself? If we suppose that these threads really pierce the 

 latter, and are continuous with the intranuclear fibres, on 

 rupture of them the nucleoplasm would probably incline 

 to shrink, endosmosis setting in would expand the outer 

 membrane and at the same time contract the apertures 

 in it tlirough which the threads pass ; on the membrane 

 swelling out then some of the threads at least would tend 

 to snap and be carried with it in expanding. This 

 attempted explanation is given as the only one which 

 seems feasible, and in harmony both with the phenomena 

 here observed and those accompanying division of the cell. 

 In treating of cell division the nature and origin of the 

 nuclear membrane will further be discussed. 



The nuclear substance of cells which have been stained 

 with logwood, eosin, chromic acid solution of heliocin, or 

 * Quart. Micro. Jour. 1878 



