Tile Identification of Intracellular Structures. 115 



followed by Altmann's stain, or alone, and some of the silver 

 nitrate or gold chloride methods which seem to give true stains. 

 All these methods (excluding the last) are extremely intense and 

 suitable for use after fixation in chrome-(">smium mixtures, which 

 necessitate a stain which will " bite in.'" In every case the above- 

 mentioned stains are best used only after constant practice. Lately 

 certain workers (including myself) have been getting beautiful 

 results by fixing in chrome-osmium, staining intensely in dense 

 hasmatoxylin such as that of Benda or Heidenhain, or Mallory (>♦?), 

 then under-differentiating, and subsequently staining in Altmann's 

 acid fuchsin and picric acid. The latter differentiates the sections 

 to the correct stage. I have also got remarkable results by fixing 

 in chrome-osmium, staining in a black hfematoxylin, and counter- 

 staining in acid fuchsin-picric acid (Van Gieson). 



The widely published statement that Altmann's acid fuchsin 

 picric acid produces granules (precipitate) in cells, and that 

 Altmann's granules are artefacts, is absolutely false. Altmann's 

 method merely stains very efficiently bodies which can be seen in 

 the fresh cell. Fischer's {19) critique is incorrect, and is due to 

 his ignorance of cytology. 



On the Chemical Constitution of Mitochondria and 



GoLGi Apparatus. 



Both Golgi apparatus and mitochondria I believe to consist of 

 a substratum of living protoplasm denser than the surrounding 

 medium in which they lie. In the first place, therefore, I consider 

 that an inquiry into the structure of these cell organs is an 

 inquiry also into the structure of living protoplasm. Besides the 

 basic protoplasmic part of both mitochondria and Golgi apparatus, 

 there are other substances present associated with the basic proto- 

 plasm. It is such associated matter which focuses our attention 

 on these cell organs and enables us to fix and stain them specific- 

 ally. I believe that the well-known changes in fixing and staining 

 affinities undergone by these cell organs are caused by the varying 

 qualities, and even absence and presence, of the associated sub- 

 stances of mitochondrium or Golgi rod. Faure-Fremiet {^5) 

 describes how he extracted a lipin or phosphatide from desiccated 

 Ascaris ovaries, and has given some account of its properties. In 

 the first place I am not satisfied that Faure-Fremiet has extracted 

 the lipin from the mitochondria alone, for in Ascaris one gets two 

 sorts of yolk and numerous Golgi rods, all of which might, and 

 probably did, contribute towards Faure-Fremiet' s extract. Before 

 the latter observer can produce evidence of a satisfactory nature 

 he must remove his mitochondria by some method whereby contact 

 with yolk and Golgi rods is avoided. According to Faure-Fremiet 



