September 10, 1915] 



SCIENCE 



349 



into protoplasm, while the beta bodies are at 

 this stage of development essentially a residue 

 ■which later in cytomorphosis, possibly only 

 after the circiilatory system has assumed its 

 nutritive role, may undergo further digestion. 

 This interpretation is further supported by 

 the fact that janus green manifests much 

 greater toxicity than does neutral red vrhen 

 embryos are grown in like dilutions of these 

 dyes. This difference in toxic action becomes 

 intelligible when one recognizes that it is the 

 processes that are leading up to the construc- 

 tion of protoplasm that are obstructed by the 

 reaction of janus green with the cell, whereas 

 it is only the residue, so to speak, of these 

 processes that is attacked by the neutral red. 

 The latter dye has, however, a very considerable 

 toxic action, the intracellular effects of which 

 can be readily recognized. The yolk globules 

 of embryos that have grown some time in a 

 solution of neutral red have enormous, deeply 

 stained red excrescences upon their surface. 

 Many small structures like beta bodies in the 

 fresh smears of living cells occur also under 

 such conditions. The excessively large ex- 

 crescences, which form large buds and separate 

 into deeply staining, small globules, can not 

 be regarded, of course, as perfectly normal. 

 Neither are they degeneration products in the 

 strict sense, for, as noted above, they do not 

 occur on globules of degenerating tissues. 

 They should be regarded, rather, as the result 

 of normal processes that have been obstructed 

 by the reaction of the products with the dye. 

 That there is a more stable chemical compound 

 established here is evidenced by the fact that 

 these excrescences can be fixed with ammo- 

 nium molybdate and preserved in microscopic 

 sections, whereas neutral red stains of other 

 structures in the cell can not be preserved by 

 this method. Unusually large excrescences, 

 also, which I have frequently seen on alpha 

 globules, are probably the expression of the 

 toxic action of janus green. 



The experiments which have led me into 

 this field began as a search for a method of 

 detecting polarity in cells and physiological 

 gradients within the embryo, my purpose being 

 to correlate my work on the growth of the 



reflex arc in its relation to the development 

 of behavior with recent researches upon gra- 

 dients in lower organisms, particularly by 

 Child.^ In their bearing upon this original 

 plan my results seem to justify the use of 

 janus green and neutral red as indicators of 

 digestion and assimilation of yolk in amphib- 

 ian embryos. Beyond this, it seems to me, my 

 observations give a clue, not only to the 

 mechanism of intracellular digestion and as- 

 similation of yolk, but also to the nature of 

 the toxic action of the dyes that have been 

 employed. My observations, however, are not 

 presented here as conclusive evidence. They 

 require critical review and extensive corrobora- 

 tion. But, awaiting the opportunity of an- 

 other season, I feel justified in making this 

 preliminary report, particularly in the hope of 

 enlisting the interest of other biologists in the 

 amphibian embryo as a unique source of in- 

 formation upon important phases of cellular 

 biology. It would be interesting to know, for 

 instance, the eytological side of the toxic 

 action of the phenolic compounds which Gort- 

 ner and Banta* used on amphibian embryos. 

 With reference to mitochondria, my interpre- 

 tation that they are derived in the amphibian 

 embryo from yolk through the formation of 

 structure which I call " alpha bodies " is 

 wholly in accord with the conclusion of Cowdry^ 

 that mitochondria are associated with me- 

 tabolism, and it is not at variance with the 

 <ybservations of M. E. and W. H. Lewis' that 



3 Child, C. M., ' ' Studies on the Dynamic 

 Morphogenesis and Inheritance in Experimental 

 Eeproduction, VIII., Dynamic Factors in Head- 

 determination in Planaria," The Journal of Ex- 

 perimental Zoology, Vol. 17, No. 1. 



4 Gortner, E. A., and Banta, A. M., "Notes on 

 the Toxicity of Dilute Solutions of Certain Pheno- 

 lic Compounds, etc.," Biochemical Bulletin, Vol. 

 3, Nos. 11, 12. 



5 Cowdry, E. V., ' ' The Comparative Distribu- 

 tion of Mitochondria in Spinal Ganglion Cells of 

 Vertebrates," The American Journal of Anatomy, 

 Vol. 17, No. 1. 



« Lewis, M. E., and W. H., "Mitochondria (and 

 Other Cytoplasmic Structures) in Tissue Cul- 

 tures," The American Journal of Anatomy, Vol. 

 17, No. 3. 



