476 E. V. Cowdry, 



2. The neurosomes of Held. 



Held published the details of his erythrosin-methylene blue method 

 in 1895, and by means of it described certain granulations in nerve 

 cells which he called "Neurosomes". Two years later he included 

 under the same heading bodies which he observed in preparations 

 made by Altmann's method (bioblasts) and in specimens fixed in pot- 

 assium bichromate and stained by Heidenhiain's iron hematoxylin 

 method. He thought (1895, p. 412) that the erythrosin-stained gran- 

 ules constitute the fibrils of Schnitze, and also (1897, p. 240) that 

 the neurofibrils of Dogiel are rows of neurosomes. The neurosomes 

 have subsequently been described and discussed by Hatai (1903), Avho 

 devised two special methods for their demonstration, and by many 

 others. In 1906 Held modified his former statement by declaring 

 (p. 185) that the neurosome-containing neuroplasma comprises also 

 special and conspicuous structural elements, the neurofibrils, which 

 were described by Max Schnitze. Finally, Martin Heidenhain (1911, 

 p. 829) affirmed that the neurosomes are neurofibrils stained in an 

 incomplete and discontinuous fashion. 



The identity of the granules which Held observed by his ery- 

 throsin-methylene blue method, the Altmann technique, and by his 

 modification of the iron hematoxylin method of Heidenhain is doubtful. 



1. The erythrosin-methylene hlue method. — Held gives the details 

 of this procedure after fixation in Van Gehuchten's fluid, 96*^/0 alcohol, 

 picro-sulphuric acid, l^^/^ sublimate in 40% acetone, and a 1:500 

 aqueous solution of chromic acid, in his first paper (1895, p. 399). 

 I have easily duplicated his results in the case of all the fixations. 

 The tissues fixed in Van Gehuchten's fluid gave by far the most 

 brilliant preparations, for in them the neurosomes could be seen as 

 very minute red-stained granules of more or less irregular shape and 

 staining affinities, standing out sharply against a colourless background 

 (fig. 12). These bodies occur throughout the cytoplasm. They are 

 most abundant between the Nissl bodies (stained blue) in the central 

 portions of the cell, also especially in the region of the axone hillock, 

 where they tend to be arranged in rows; but they occur, though less 

 thickly, in a peripheral zone of cytoplasm which is free from Nissl 



