30 Journal of Comparative Neurology and Psychology. 



nucleus also occurs in the cells of the adult animal. The shape 

 of the nuclei is somewhat oval, the longer diameter being per- 

 pendicular to the long axis of the protoplasmic process. On 

 one side towards the center of the cell, the outline of the 

 nucleus is more or less wavy. In some cases, the wavy out- 

 line is not very marked (Fig. 5) but in most cases, it is con- 

 spicuous and one is lead to compare it to the pseudopodia-like 

 process of an amoeba (Figs, i, 2, 4). 



The nuclei showing the pseudopodia-like processes have 

 been observed by several investigators; in the egg nuclei of the 

 insects and Coelenterata by Korschelt ('89) ; in the spinning 

 gland cells of a Swedish caterpillar and also in the spinal gang- 

 lion cells of the fishes, frogs, etc.. by Holmgren ('95 '00) ; in 

 the developing ovum of the Nassa by Hoffmann ('02) ; in the 

 nuclei of the ventral horn cells of various vertebrates by Kol- 

 STER ('01) ; and the same thing is also shown in the illustrations 

 accompanying a large number of papers in which, however, the 

 authors do not describe this interesting phenomenon. Before 

 going on to a further discussion of this appearance, I shall de- 

 scribe more in detail the histological characters of the wavy 

 outline together with the structure of the adjoining part of the 

 cell body which contains the centrosome. 



The neuclear membrane which covers the pseudopodia is 

 not completely continuous but is composed of separate portions 

 when seen in thin sections ; in other words, the surface of the 

 nuclear membrane towards the cytoplasm is porous. A disap- 

 pearance or dissolution of the membrane on this side of the nu- 

 cleus has been observed by Holmgren, and Pugnat ('98), but 

 in the case of the white rat, it is always porous in character. 

 This is clearly shown in Fig. 2. In many cases, however, the 

 local dissolution of the nuclear membrane is not as conspicuous 

 as in Fig. 2, but the outline appears varicose in structure owing 

 to an accumulation of basophile granules around the pores 

 (Figs. 2, 5). 



The nuclear membrane which lies towards the protoplasmic 

 process is of uneven thickness. The thicker portions stain 

 much more deeply than the rest of the membrane with the 



