226 



PLANT PHYSIOLOGY 



The Klinostats so far described are either normal or precision forms, 

 but a number of adapted types have been invented. Thus aside from a crude 

 Klinostat centrifuge, made from clock works, described by Swezey in the 

 Botanical Gazette, 16, 1891, 147, Stevens has described a simple form run 

 by a water-motor (Botanical Gazette, 20, 1895, 92); Stone gives one run 

 by clockwork (Botanical Gazette, 22, 1896, 259), and I have myself de- 

 scribed a good form, constructed from the works of a powerful clock, in 

 the Botanical Gazette, 27, 1899, 258, an instrument which, by the way, 



Fig. 64. — Frame for demonstration or geotropism 



Explanation in text. The lower counter-weight should be shown hanging on a wire loop 

 which turns on the frame. 



would be much improved by using a box of wire netting instead of the crys- 

 tallizing dish. Still simpler arrangements approaching the make-shift char- 

 acter, and revolving but once an hour (which is sufficient for some of the 

 simplest uses), have been described by Osterhout, 91, by Stevens in his 

 "Introduction to Botany" (Heath & Co., 1902), 25, and by others. 



The limitations of Klinostats, and the proper principles in their con- 

 struction and use, have recently been discussed by Newcombe in Science 

 20, 1904, .376, and by Van Harkeveld in his paper cited above. 



