ADMINISTRATIVE FUNCTION OF THE NUCLEUS 31 



In Brassica Na/pus some of the root-hairs branch, while remaining 

 unicellular ; in these the nucleus always lies in the branch which dis- 

 plays the most active growth in length. On the basis of the facts 

 detailed above, and in consideration of a number of similar observations, 

 the author has come to the conclusion that the nucleus exerts a direct 

 influence upon the growth and differentiation of every cell. In view 

 of what has been stated above, one 

 is tempted to assume that it is 

 the presence of the idioplasm 

 which endows the nucleus with 

 this power of organisation and 

 administration. 



The author's observations upon 

 the connection between the posi- 

 tion of the nucleus and its admini- 

 strative functions have since been 

 confirmed and supplemented by 

 several other investigators. "With 

 regard to the recent work upon 

 this subject, it will only be neces- 

 sary to discuss some of the facts 

 discovered by Magnus, by Shibata, 

 and by Guttenberg ; all these 

 observers attach a definite physio- 

 logical significance not only to the 

 location of the nucleus, but also to 

 the shape assumed by this organ. 



The roots of Neottia Nidus oris 

 contain a fungus-mycelium which, 

 in certain cells, becomes aggre- 

 gated into dense coils of hyphae 

 containing an abundance of proto- 

 plasm ; sooner or later these coils 

 die, whereupon their contents are 

 rapidly digested and absorbed by 



the " host-cells." The undigested remnant of each coil becomes 

 compacted into a " clump " and surrounded by a sheath of protoplasm, 

 which subsequently becomes transformed into a substance resembling 

 cellulose. The latter part of the process suggests an act of excretion, 

 whereby the indigestible portions of the mycelium are rendered 

 innocuous. Now Magnus has noted that the nucleus of the host- 

 cell always adheres closely to the clump ; moreover, on the side 

 nearest the clump the nucleus loses its definite outline, and may 



Fig. 3. 



Location of the nucleus iu growing cells. 

 A. Origin of root-hairs in Pisum sativum. B, C. 

 Formation of a papilla in the outer wall of an 

 epidermal cell of Aloe verrucosa. D. Thickening 

 of the inner epidermal walls in the testa of 

 Scopolina atropoides. 



