June i, 1915] 



SCIENCE 



835 



described by Tsebascliiii, Evans and Sebule- 

 mann, and others, the two common types of 

 connective tissue cells are readily distinguished 

 by their reaction to the vital stain, the clasma- 

 tocytes storing large masses, the fibroblasts 

 much more minute granules of the dye. It can 

 not be denied that the delicate punctate and 

 rod-like deposits of isamine blue, as seen in 

 fibroblasts, often make an astonishingly close 

 approach to mitochondria in appearance. But 

 are they mitochondria? This question could 

 only be answered by applying to the cells in 

 question the criteria for the recognition of 

 mitochondria, which are well known to cyto- 

 logical technique. We have confined ourselves 

 to three methods, which have been pursued 

 until they yielded constant and reliable results. 

 These are the iron hematoxylin method, the 

 aniline acid-fuchsin methyl-green method 

 (Bensley), and supra- vital staining with janus 

 green (Michaelis, Laguesse, Bensley, Cowdry). 

 On studying in this way the fibroblasts of the 

 mouse, mitochondria can easily be demon- 

 strated. They disagree in several respects with 

 the alleged isamine blue mitochondria. The 

 true mitochondria are always scantier in num- 

 ber than the deposits of isamine blue which 

 occur in fibroblasts of chronicly stained ani- 

 mals, and they are more definitely threadlike 

 than the isamine blue structures. Further, it 

 is quite possible to see the unstained mito- 

 chondria lying between the isamine blue 

 granules in living cells, examined immedi- 

 ately after removal from the body, and finally, 

 by staining with janus green, one can see these 

 previously unstained structures now add them- 

 selves to the number of stained cytoplasmic 

 elements, where their peculiarities as regards 

 color, shape, size and arrangement are still 

 retained. These conclusions obtain even more 

 emphatically with trypan blue and presumably 

 with all of the benzidene dyes. 



In the vital staining with azo dyes, it is not 

 true, consequently, as Tschaschin maintains, 

 that we have a vital staining of the mitochond- 

 rial apparatus in some cells, in addition to the 

 gross reception of the dye by the macrophages. 

 Indeed, Tschaschin believes that in the macro- 



phages themselves the mitochondria are stained 

 vitally, but that here they are exclusively 

 granular, spherical forms, and suifer all stages 

 of transformation into the large " secretory " 

 granules. The methods detailed for the study 

 of fibroblasts yield essentially similar results 

 when applied to the macrophages. These, in 

 contradistinction to the claim of Tschaschin, 

 have true mitochondria, some of them filiform, 

 among the azo dye granules. 



This discussion has wider implications, for 

 Tschaschin's ideas have been accepted by 

 Kiyono even though he recognizes some anom- 

 alous aspects of such a conclusion. Kiyono 

 seems willing to believe that the macrophages 

 may react to these dyes in a phagocytic or phys- 

 ical way but that this can not be the explana- 

 tion for all the granules produced by these 

 dyes, since the reception and storage of foreign 

 substances by some of the other cells which are 

 vitally stained is a phenomenon unknown by 

 other methods. This argument seems beside 

 the point. We can only state that in no case 

 known to us have the granules produced by 

 vital azo dyes been found to be identical with 

 the mitochondria of the vitally stained cells. 



Katherine J. Scott 



TSE AMEBICAN PHILOSOPHICAL SOCIETY 



The annual general meeting of the American 

 Philosophical Society was held in the rooms of the 

 society in Philadelphia on April 22, 23 and 24. 

 The meeting was opened on Thursday afternoon by 

 President W. W. Keen, who, with Vice-presidents 

 A. A. Michelson, W. B. Scott and Professor C. L. 

 Doolittle, presided over the various sessions. 



On Friday evening a reception was held in the 

 hall of the Historical Society of Philadelphia, at 

 which William Morris Davis, Se.D., Ph.D., pro- 

 fessor emeritus of geology. Harvard University, 

 gave an illustrated lecture ' ' On New Evidence for 

 Darwin's Theory of Coral Eeefs." The lecture 

 described the chief results of a Shaler Memorial 

 Voyage across the Pacific in 1914, with studies of 

 the Fiji group, New Caledonia, the Loyalty Is- 

 lands, the New Hebrides, the Great Barrier Eeef 

 of Australia and the Society Islands. 



On Saturday afternoon a symposium was held on 

 the Figure, Dimensions and Constitution of the 

 Interior of the Earth. The subject was discussed 



