CYTOPLASMIC STRUCTURES IN THE SEMINAL EPITHELIUM OF THE OPOSSUM. 79 



whom the chondriosomes and apparatus are two different things, believes that "en 

 las neuronas adultas, la despolarizacion del aparato de Golgi y su difusion peri- 

 nuclear coincide probablemente con la atrofia y desaparicion de la esfera y cen- 

 trosoma (p. 209)." This opinion is plausible only if, as Cajal himself indicates, 

 it is limited to mammals, and further, if it is well understood that "esfera" and 

 "centrosoma" do not mean "centrioles," a confusion which is too often made. 



As to the non-nervous cells Ramon y Cajal (1914, p. 208), after extensive 

 observations on the apparatus in embryonic, cartilaginous, epidermic, and glandu- 

 lar cells, in odontoblasts and osteoblasts, in fat and goblet cells, subscribes whole- 

 heartedly to my opinion: 



"Desde las clasicas investigaciones de Ballowitz, efectuadas en el epitelio posterior 

 de la cornea, y confirmadas despues para otros tejidos por numerosos autores (Negri, 

 Pensa, Barinetti, Terni, Perocito, Deineka, etc.,) quedo perfectamente estahlecido que, 

 en toda celula portadora de un reticulo endocelular polarizado y concentre do, existe en el 

 centre de este un hueco donde se aloja la esfora atractiva. Numerosos indicio confirma- 

 torios de esta conexion hemos consignado tambien nosostros al describir la disposicion del 

 aparato de Golgi en las grandulas, osteoblastos y osteoclastos y durante las fases onto- 

 genicas de las neuronas y corpusculos epitelicos. En este punto suscribimos de buena 

 gana el pensiamento de Duesberg (1914), para quien el aparato de Golgi estaria primera- 

 mente ligado al sistema de la esfera atractiva " 



A further confirmation of the same opinion is found in Basile's researches 

 (1914) on the modifications of the apparatus in the renal epithelium after nefrec- 

 tomy. While normally the apparatus is located between nucleus and lumen, after 

 the operation it has moved to the basal part of the cell, and with it the centrioles. 



The relationship between the apparatus and the centers of the resting, non- 

 nervous cell appears, therefore, more and more safely estab- 

 lished. 1 The structure of a young resting cell could, in my 

 opinion, be adequately represented by the accompanying 

 schema. It should be well understood, however, that the ap- 

 paratus is not always a reticulum. Another remark of im- 

 portance is that, as a rule, in epithelial tissues the apparatus is 

 located in that part of the cell which Cajal (1914) has called the 

 "polo mundial o de relacion exterior" (see Duesberg, 1914, p. 

 21.) 2 As to the chondriosomes, their form and location vary. 



During mitosis the apparatus falls to pieces and its frag- FK^ E. 



ments are scattered all over the cell-body, or else the primitively isolated parts of 

 the apparatus behave in the same way. There appears to be in some cases con- 

 siderable regularity in the shape of these fragments, their number and their distri- 

 bution between the daughter cells. The behavior of the chondriosomes during 

 mitosis is again variable, as I emphasized recently (1917, p. 478 et seq.; see also 

 Meves, 1914, 1). 



'Cowdry (1916) does not agree with me in my "attempt to define the apparatus in terms of its relation to the cen- 

 trosome, because our knowledge of the centrosome itself is so deplorably inadequate (page 40)." If this applies to the 

 non-nervous cells as well as to the nerve-cells, I certainly do not agree with Cowdry's skeptical attitude, either towards the 

 relationship of the apparatus to the centers, or towards our knowledge of the centrosome. 



2 The similar location of the centrioles is, since the researches of K. W. Zimmerman and Heidenhain, well known. 



