THE PROBLEM OF MITOGENETIC RAYS 



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too much on the correctness of the wave-length of these spectra since, as 

 mentioned before, the physical technique was such that a displacement of 

 an entire spectrum for as much as 100 A units does not seem at all 

 impossible. 



The greater part of the work on the application of the mitogenetic-ray 

 technique has been done with animal materials and only relatively little 

 with plant material, with the exception, of course, that the latter have 

 been used extensively as detectors — in growth effects. Onion sole was 

 one of the first senders used in mitogenetic work. This material consists 

 of a pulp made by grinding the medullary plate of the onion bulb. 



Following the chemical experiments of Du Bois and of Harvey (141) 

 on the two enzymes, luciferine and luciferase, — Gurwitsch (97) reports 

 he was able to separate two sub- 

 stances from a pulp made by grinding 

 up the medullar plate of the common 

 onion (see Table 1). He calls these 

 two substances mitotin and mitotase 

 and says they behave like luciferine 

 and luciferase. This reaction gives a 

 typical oxidation spectrum. The 

 radiation given up at the root tip 

 apparently does not have its origin 

 there but rather in the medullar plate, 

 and it is transmitted through secon- 

 dary radiation to the root tip. That segment of onion root: 1, segment of 



*' '^ onion root; 2, rotating disk with cutouts; 



distance is often 10 to 15 cm. The 3, yeast agar block (sender); 4, entrance 



spectrum of the root-tip radiation is «"t of quartz spectrograph. (After 



^ ^ Gurwitsch, 108.) 



of glycolytic origin. Thus the secon- 

 dary radiation does not necessarily have the spectrum of the pri- 

 mary radiation in it. A cut segment of root which otherwise would 

 not radiate may also be brought to radiation by an oxidation reaction, 

 as explained in Fig. 7. Besides onion material, damaged leptome bundles 

 of potatoes (155), the cotyledons of Helianthus, a mash of yellow-beet 

 tissue (80, 102), and the pulp of Sedum latifolium (108) are serviceable, 

 if kept over night at low temperature, but not the fresh material. For 

 negative results on the last-mentioned materials see Haberlandt (139). 

 Bacteria (1, 2, 8, 13) and yeast (12, 14, 38, 292) during the "log" 

 stage of their development are good senders. Yeast can be used as 

 detector or sender only in the presence of some visible light (213). Since 

 these organisms can be senders as well as detectors, we have in each sus- 

 pension what has been called "mito-induction." That these organisms 

 in dense suspensions grow faster than in very dilute suspensions is one of 

 the features pointing toward the radiation explanation. However, 

 workers in the field have not as yet explained how this concept fits in 



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Fig. 7 — Arrangement for spectral 

 analysis of secondary radiation from a 



