THE VISIBLE EFFECTS OF THE SCHUMANN RAYS 
ON PROTOPLASM®* 
W. T. BOvViIE 
Since the pioneer studies of DowNEs and Biunt, a large num- 
ber of investigators have studied the effects of ultra-violet light 
on protoplasm. Their investigations, however, have all been 
made on the effect of light of wave lengths longer than 2000 Ang- 
strom units. This paper is a preliminary report of the visible 
effects produced in protoplasm by light waves shorter than 2000 
Angstrom units. 
When studying the biological effects of light, it is convenient 
to divide the spectrum into the following regions: 
Regions Wave lengths in Angstrom units 
Ene OO Gia es or ec ee ee from 10,000 to 7,200 
VM oe sien ia ae cee ieee 9,200 ** 4,000 
Ultra-violet of sunlight................. POO 2.060 
Quarte Wittavalet. 6 oe Nog oso “reo 
Pinorikte witth-vinket ; . 50s fie See 8.950 
(Schomann regio. ose orc ace <). 3,pob: Ss a6e) 
RAN POMS 6 oe i oe ca een eee FAs Sats 8 
To this series we may add Réntgen rays with wave lengths from 1 to 0.1 
Angstrom units, and gamma rays with still shorter wave lengths. 
The effect on protoplasm of light of the Schumann region of 
the spectrum is particularly interesting because in this region oi 
the spectrum the destructive action of the light is much more 
violent than it is in regions of longer wave lengths. This violent 
action is undoubtedly connected with the fact that the Schumann 
region of the spectrum is a region of general absorption for nearly 
all substances. Even substances as transparent as air and water 
absorb the shortest Schumann rays. A layer of air 1 cm. thick 
or a layer of water only o.5 mm.3 thick absorbs all except the 
longest Schumann rays. Fluorite, the most transparent substance 
? Preliminary communication, 2 10,000 Angstrom units=1 micron, 
3 Lyman, T., Astrophysical Jour. 27:87. 1908; Nature 84:71. 1910. 
149] {Botanical Gazette, vol. 59 
