5IO MONTGOMERY. [Vol. W. 



beke ('97b), Mark ('77), Bancroft ('98). Compare also the follow- 

 ing : Huie ('97), Van Bambeke ('97), Kosinski ('87, '93), Mark 

 ('77), Zimmermann ('96), Hodge ('94). I have found these bodies 

 occurring in varying number, though most frequently absent, 

 in the nucleoli of various cells, and they appeared to be merely 

 loosened portions of the ground substance which had come to 

 lie within a vacuole. Macfarlane and his pupil Mann have 

 described nucleolini under the names " endonucleolus " and 

 " nucleolo-nucleus " as occurring singly and with great con- 

 stancy in certain plant cells, though Zacharias ('85) studied 

 Macfarlane's object {Chard) and makes no mention of any of 

 these structures. Macfarlane ascribes the utmost importance 

 to his " endonucleolus," regarding it as the tropic center of the 

 cell and as an important mechanical agent during nuclear 

 division. Mann has not only described a most complex struc- 

 ture of the nucleolus, such as no other observer has yet seen, 

 but also has found fine fibrils radiating out from it, which he 

 supposes to penetrate through the nuclear cavity. From my 

 own observations, and in agreement with the majority of ob- 

 servers, I can attach no particular morphological significance to 

 the nucleolinus ; it appears to be only a detached portion of 

 the nucleolar ground substance, to be in most cases absent, 

 and when present to vary greatly in regard to size, position, and 

 number. It is undoubtedly the case that many structures 

 which have been described as nucleolini are in reality minute 

 vacuoles, which from their refrangibility appear to be granules ; 

 such is the case with the minute vacuoles of Polydora and 

 Montagiia when studied after the action of certain stains, and 

 has been shown for other objects by Zimmermann and Huie, 

 Lavdowsky found in the nucleolus a central vacuole, and in 

 the latter a small granule, which he supposed to be "das noch 

 in Entwicklung begriffene Centrosoma," destined to finally 

 pass out of the nucleolus ; he was unable to determine how 

 it does wander out of the nucleolus and become the centrosome, 

 so that his suggestion has merely the value of a hypothesis. 

 Van Bambeke describes the nucleolinus of the germinal spot 

 of Amanrobiiis as " dou6 d'un mouvement tres vif " ; this 

 interesting phenomenon certainly deserves investigation, though 



