258 BULLETIN OF THE 



mandra, Langerhans ('71, p. 16, Fig. 6, '73«, p. 750, Taf. XXXL Fig. 11) con- 

 firms Elmer's observation. It may be added that Eberth ('63, Taf. XIV. 

 Fig. 2) long ago figured nuclei from the ephlthelial lining of the triton's lung 

 presenting similar features. 



S. Mayer ('72, p. 812) says, " The substance of the nucleus [sympathetic 

 nerve cell] is not homogeneous ; there may be observed in the same fine fila- 

 ments (Fiiden) which arise from the nucleolus." Although unable to find a 

 communication of the cell processes with the nucleus or nucleolus, he reports 

 a little further on (p. 817) his conviction that, very often, in addition to the 

 processes of relatively large calibre which arise from the cell-substance itself, 

 still a second system of very fine filaments emerges from the cells which take 

 their origin in the nucleus and nucleolus. 



As part of a scheme of extensive, if not universal, applicability to the 

 structure of protoplasmic bodies, Heitzmann ('73 and '73«) maintains for the 

 nucleus a reticulation, which is continuous with a similar network of the sur- 

 rounding cell-protoplasm. The reticulated structure, however, is an indication 

 of a certain advance in the age of the protoplasmic body. " The originally 

 quite homogeneous mass of protoplasm becomes differentiated at its periphery — 

 with accompanying increase in circumference — into a network, while the 

 centre — the nucleus — remains homogeneous. Then follows a differentiation 

 in the central mass (nucleus) into a Fachwerh, and later into a network, so that 

 here also compact, smaller centres remain as nucleoli." 



Finally, the differentiation has taken place in the whole protoplasmic body. 

 Thus the disappearance of the nucleus is followed by that of the nucleoli ; the 

 whole body is now only a network with coarser or finer nodal points, and this 

 condition immediately precedes in tissues the formation of a " Grundsubstanz " 

 ('73, pp. 155-158, and '73«, pp. 46, 47). 



These general conclusions are supported by observations of vacuolation in 

 Amoeba ('73, p. 101, '73«, p. 42) ; by studies on blood corpuscles of Astacus* 

 ('73, p. 105); on white blood corpuscles of man ('73, p. 107); on cartilage cells 

 ('73, p. 142, and '73«, p. 43) ; on ganglionic corpuscles of the brain and sympa- 

 thetic centres ('73, p. 153); and on some other structures. 



■ The nucleolus, the nucleus, the granules, and their filaments are the strictly 

 living, contractile material, and this contains in its reticulations, and encases as 

 a shell, a non-contractile fluid material, which, however, cannot be pure water.f 



* In this case the corpuscles suffer a vacuolation resulting in a network which 

 gives the protoplasmic reaction with chloride of gold, while the vacuoles remain 

 colorless. 



t The existence of an extra-nuc\ea.r network in the peripheral cells of the salivary 

 glands of Blatta has been established by the researches of Kupffer ('74, pp. 78-81), 

 who is not inclined to ascribe a passive importance, or even subordinate function, to 

 the more pellucid, non-fluid " Grundsubstanz " through which the network runs. 

 Compare also Kupffer's ('75) studies on the liver cells of the frog, etc. 



An extranuclear reticulum of greater or less extent has been seen by many other 

 observers in various tissues, but especially in nerve cells from the time of Stilling to 

 Frommann, Trinchese, Ciaccio, and others. 



I 



