February 27, 1914] 



SCIENCE 



331 



driomiten by Benda ; chondrioconteii, chondrio- 

 somen, chondrion and plastosomen by Meves; 

 plasmafaden, plasmakoner by Retzius; para- 

 miton or miton by Flemming; microsomen by 

 Van Beneden; granule and filament by 

 Altmann. 



The mitocliondrial theory has been most 

 widely promulgated by Benda (1899-1903) 

 and Meves (1907-1908). Duesherg states the 

 theory concisely as follows: the mitochondria 

 are specific elements of the cytoplasm, which 

 arise from preformed elements in the male and 

 female sex cells and are carried over into 

 every cell at mitosis. These bodies differentiate 

 into specific parts of the various adult tissues. 

 While there are many authors whose observa- 

 tions tend to substantiate the mitochondrial 

 theory, on the other hand just as many writers 

 refuse to accept the mitochondrial theory in 

 its entirety. Some give observations to show 

 that the mitochondria are formed from nuclear 

 material at certain periods of the cell's 

 activity.^ Others claim that they are fermen- 

 tation products of the activity of the centriole,^ 

 and still others state that the mitochondria are 

 throughout entirely different elements whose 

 identity have nothing in common.* 



The tissues from chick embryos grown out- 

 side the body in media of known chemical con- 

 stitution, which we have been studying during 

 the past three years, with other problems in 

 mind, have shown such beautiful mitochondria 

 in both fixed and living specimens that we are 

 led to believe this method offers a better oppor- 

 tunity for their study than any heretofore 

 used. 



Small pieces of tissue from a chick embryo, 

 four to ten days old, suspended in a drop of 

 Lock's solution containing 0.25 per cent, dex- 

 trose are placed on the sterile surface of a 

 clean coverslip. The coverslip is then inverted 

 over a hollow ground slide, sealed with vase- 

 line, and incubated at 39° C. ; growth usually 

 appears at the end of 10-20 hours. Such 

 preparations are studied on the warm stage 



2R. Hertwig and Goldsmith, 1909. 

 sVejdovsky, 1907. 



4Veratti, 1909; Pensa, 1911; Linidegard, 1910; 

 Curwitsch, 1910. 



with the No. 2 Zeiss apoehromatie and a No. 

 4, 6 or 8 ocular. 



Janus green in strengths of .00001 and 

 .000005 of 1 per cent, stains the mitochondria 

 in the living cells a brilliant blue green. The 

 color fades, however, in from 15 minutes to 3 

 hours, and we have been unable to restain. 

 The janus green is also slightly toxic and kills 

 the cells in a few hours. We are indebted to 

 Dr. E. V. Cowdry for this particular janus 

 green (di ethyl saffranin azo di methyl aniline) 

 which was obtained by him from Dr. Bensley 

 of Chicago. Attempts to stain with another 

 make were unsuccessful. 



Nilblew B. extra, for which we are in- 

 debted to Dr. Herbert Evans, was used in 

 very dilute solution of .000005 to .0000025 of 

 1 per cent, for the detection of lipoids in con- 

 nection with the mitochondria. It stains the 

 lipoids pink, but is unfortunately somewhat 

 toxic and, like the janus green, kills the cells 

 in a few hours. 



The preparations are fixed by placing the 

 coverslip in a chamber of osmic acid vapor 

 from two to five minutes and since the growth 

 is very thin, the fixation is almost instantane- 

 ous and tlie mitochondria remains practically 

 the same as in the living cells. The blacken- 

 ing caused by the osmic is bleached during the 

 hardening processes by means of a few drops 

 of hydrogen peroxide in the 70 per cent, alco- 

 hol and the preparations are then stained with 

 Heidenhain's iron hematoxylin. Since in 

 places the cells are flattened out on the under 

 surface of the coverslip into a single layer 

 much thinner than the usual thickness of a 

 single cell, one can study the entire living cell 

 and its contents with a minimal amount of 

 focusing. Also at any moment during the 

 observations the culture can be fixed and 

 later the same cells studied in a stained prep- 

 aration. 



Mitochondria were studied in endothelium, 

 mesenchyme, giant cells, ectoderm, heart 

 muscle, smooth muscle and endoderm. 



The stained preparations show great variety 

 in the shape of mitochondria and often in the 

 same specimen, as of heart muscle or mesen- 

 chyme, all the so-called types described by 



