296 MONTGOMERY. [Vol. XV. 



Carnoy ("84) distinguishes three kinds of nucleoli : (i) "nucle- 

 oles nucleiniens," which are parts of the chromatin network ; 

 (2) " nucl^oles-noyaux," which contain all the elements of a 

 normal nucleus (namely, a membrane, chromatic filament, and 

 nucleolar substance), while the substance in the remainder of 

 the nucleus is allied to cytoplasm ; such nucleoli occur in 

 Gregarines, large Radiolaria and Rhizopoda, Spirogyra, the asci 

 of lichens, testicle cells of Littobius, and eggs of P leurobrachia, 

 Ascidia, and Nephthys ; (3) " nucMoles plasmatiques," which 

 contain no chromatin, but consist of a plastin network in 

 which an albuminous enchylema is imbedded. 



Frommann ('84) studied fresh ganglion cells from the anterior 

 horn of the medulla of the o.x ; their nucleolus shows " eine 

 Zusammensetzung aus feinen und derberen Kornchen und aus 

 sehr kurzen Faden, mitunter auch einen netzformigen Bau mit 

 theils ganz engen, theils etwas weiteren Maschen." In the 

 ganglion cells (of the ganglion Gasseri) of the rat, the nucleolus 

 is usually homogeneous, as are those of the sympathetic ganglion 

 cells of Bi(fo. 



R. Hertwig ('84), Actinosphacrhini : in the resting nucleus 

 there is one central nucleolus which consists of deeply staining 

 nuclein and faintly staining paranuclein. The nucleolus is 

 rarely spherical ; when so, it consists mainly of nuclein, except 

 for a small portion of paranuclein superimposed on the margin. 

 In other cases the larger nuclein portion is of a curved dumb- 

 bell shape, and " gleichzeitig bildet das Paranuclein ein schwach 

 gekriimmtes Stabchen, dessen Kriimmung zur Kriimmung der 

 Nucleinmasse senkrecht gestellt ist." The connecting portion 

 of the dumb-bell may disappear, " so dass sich zwei Nucleoli 

 bilden, welche von einander durch ein queres Stabchen Para- 

 nuclein getrennt werden. . . . Hiermit beginnen die plurinu- 

 cleolaren Kerne, wie sie fiir gewohnlich bei Actinosphaerium 

 beobachtet werden." In most nuclei there lies a mass of from 

 six to twenty nucleoli, which are smaller as they become more 

 numerous: " Hier ist es sehr schwer festzustellen, was aus dem 

 Paranuclein geworden ist, und . . . bin ich zu dem Resultat 

 gekommen, dass es als ein Korn im Centrum des Haufens von 

 Kernkorperchen ist, dass es mit einem Fortsatz an jedes 



