The Microscope. 265 



wall of the tubule so as to leave an empty central canal, and fre- 

 quently it even forms regular disks with regular intervals be- 

 tween, so as to give the nuclein tubule a transversely striated 

 appearance, resembling somewhat a striated muscular fibre. 

 Whatever may be the appearance of the nuclein, one fact is 

 brought out by the researches of Carnoy, viz., it is never gran- 

 ular or in the form of microsomata, as is believed by Strasburger 

 and others. 



II. — PROTOPLASTIC ELEMENT OP THE NUCLEUS. 



The caryoplasm has a structure similar to that of the cyto- 

 plasm, i. e., a reticulum of plastin and an enchyleraa, only the 

 latter is generally more hyaline and the former less pronounced. 

 This protoplastic portion may be seen directly in many nuclei. 

 It may be seen especially in those nuclei in which the nuclein 

 tubule is more loosely packed, or when its convolutions are not 

 too numerous ; also when the nuclein is more or less contracted 

 towards the centre so as to form a nucleolo-nucleus, as is the 

 case in cells from Litliohius. 



Sometimes by cutting sections, the nuclein tubule is dragged 

 out, and then the reticulate structure of the protoplastic portion 

 becomes quite evident. 



Space will not allow me to give further evidence of the exist- 

 ence of the protoplastic portion, and therefore I must refer the 

 reader to the work of Carnoy in " La Cellule." 



III. — THE NUCLEAR MEMBRANE. 



It will be sufficient to state here that the nuclear membrane 

 presents the same organization as the membrane of Yon Mohl ; 

 it is reticulated, closed and without pores. This, however, is 

 contrary to the ideas of Leydig, Strasburger and Heuser. 



IV. — THE NUCLEOLUS. 



The existence of a nucleolus within the nucleus can no longer 

 be called into question. To reveal its presence fresh material 

 must be used, and this has to be stained with methyl green, and 

 then the nuclein must be dissolved by one of its dissolvents. 

 In this way the presence of several kinds ©f nucleoli may be 

 demonstrated. First, we find nuclein-nucleoli, which are little 

 amorphous bits of nuclein, colored by methyl green and dis- 

 solved by concentrated hydrochloric acid. Second, plasmatic 



