118 THE CELL DOCTRINE. 



bone-cells, and in the epithelium of the mouth and 

 capillary vessels. He observed clear shining fibrils pro- 

 ceeding from the nucleolus joining themselves to others 

 proceeding from the nucleus and protoplasm. From 

 the nucleoli of connective tissue arise one, two, and, 

 more seldom, three fibrils. These sometimes dwindle 

 away in the nucleus itself; at others, after a straight 

 or curved course, leave the cell and lose themselves 

 in the neighborhood. Repeatedly was observed the 

 entrance of a nucleolus-fibre into a cell process, and 

 if two cells were united by a process from each, the 

 nucleolus-fibre was seen to pass from one cell to 

 another. So also fibres originating in the nucleus, 

 sometimes as many as six in number, could be fol- 

 lowed into the protoplasm, and more seldom beyond 

 the cell. Certain fibres appear to cease in the nu- 

 cleus by a free extremity, as though cut oft'. Others 

 have attached to them glistening granules, which in 

 fresh, as well as hardened preparations, are con- 

 tained in variable number in the nucleus. Frommann 

 believes that the granules of the nucleus and proto- 

 plasm are the nodal points of a very fine fibrous net- 

 work, from which fibrils go off" and leave the cell. 

 These are found in the cells of all the tissues named 

 above. In consequence of this complicated structure 

 of the nucleus, Frommann thinks it improbable that 

 it multiplies by division ; he believes in a free new 

 formation of the nucleus in the protoplasm, where, 

 alongside of nuclei of ordinary appearance, smaller 

 homogeneous ones make their appearance. 



In ,1873,* Heitzmann asserted that the substance 



* Untersuchungen iiber das Protoplasma, Sitzungsber., d. k. 

 Akad. d. Wiss. zu Wien, Bd. Ixvii und Ixviii, Abth. iii, 1873. 



