354 MONTGOMERY. [Vol. XV. 



Held ('95) finds that in the ganglion cells of vertebrates, 

 when stained with erythrosin followed by methylen blue, the 

 nucleolus stains blue and the " Nebennucleoli " violet. 



Herrick ('95) found that the nucleolus of Homarus contains 

 one large and several smaller vacuoles ; the gravitation of the 

 nucleolus in the caryolymph, i.e., its movement to the lower 

 side of the nucleus, may be post-mortem phenomena (at least I 

 learned as much from Dr. Herrick during a brief conversation). 



Keuten ('95) investigated the nuclear division of Euglcna 

 viridis. In the nucleus there is an elongate body, the " Nucle- 

 olo-Centrosoma," which stains more intensely than any other 

 portion of the nucleus. At the commencement of mitosis it 

 elongates, "und wahrend die Segmente [Chromosomen] bisher 

 eine annahernd senkrechte Richtung zur Oberflache des Nucle- 

 olo-Centrosomas eingenommen hatten, bilden sie jetzt einen 

 spitzen Winkel mit demselben," and gradually come to lie 

 parallel to it. At this time the middle piece of the " Nucleolo- 

 Centrosoma" stains more lightly than its ends, so that these 

 latter parts are sharply demarcated from it (with the stain of 

 Heidenhain, namely, Bordeaux R. followed by haematoxylin). 

 " In der folgenden Phase riicken die parallel zum Nucleolo- 

 Centrosoma gelagerten Chromosomen von beiden Polenden her 

 nach dem Aquator zu, so dass die Enden des Nucleolo-Cen- 

 trosomes nunmehr frei in die Kernhohle hineinragen, wahrend 

 die Chromosomen als breite aquatoriale Zone das Mittelstiick des 

 Nucleolo-Centrosomes umgeben." Next, the nucleus assumes 

 the form of a rotation ellipse, in the short axis of which the 

 "Nucleolo-Centrosoma" lies. After the longitudinal splitting 

 of the chromosomes, from three to five vacuoles appear in each 

 end of the " Nucleolo-Centrosoma " ; then the latter structure 

 elongates and breaks into two parts, while at the same time the 

 long axis of the nucleus gradually changes so as to coincide 

 with the long axis of the " Nucleolo-Centrosoma," and part of 

 the chromosomes become grouped around the one end, the 

 remainder around the other end, of the "Nucleolo-Centrosoma." 

 Keuten believes his " Nucleolo-Centrosoma " to be comparable 

 to the nucleolus of Amoeba crystalligcra (Schaudinn), to the 

 " Centralspindel " in Diato7nca (Lauterborn), and to the centro- 



