along their course they show beaded swelhngs which mark the points where 

 the lumen is enlarged to enclose a mitochondrion. 



It was shown some years ago that if the sensory axon is cut, a new axon 

 grows out from the sense cell and idtimately makes its way to the central 

 nervous system. (Wiggles worth, 1953). Examination of such regener- 

 ating neurones by the osmium-ethyl gallate method shows that the sense 

 cells are enlarged and mitochondria in large numbers are moving into the 

 growing axons (WigglesAvorth, 1950a). 



The osmium-ethyl gallate method is very convenient for tissue sections. 

 The method is described in full elsewhere (Wiggles worth, 1959c). A small 

 piece of tissue is fixed for some hours in buffered isotonic osmium tetroxide, 

 rinsed in water, and transferred to a saturated solution of ethyl gallate in water 

 for twenty four hours. It is then oriented and embedded in agar, and the agar 

 block embedded in the ,, ester луах" of Steedman (1947). The final block 

 is cut Avith specially sharpened safety razor blades and the sections collected 

 on the surface of water directly onto a coverslip. The sections are dried and, 

 after removal of the wax, are mounted directly in a gum mountant containing 

 ethyl gallate in solution. By this means it is easy to obtain serial sections 

 of 0,5 [JL thickness or less. 



A number of insect tissues have been studied by this method. It has proved 

 particularly informative when applied to the nerves and central nervous 

 system (Wiggles worth, 1959b). Among other things it stains the contents 

 of the neurosecretory cells quite well (though not so conspicuously as the stan- 

 dard methods). It is also useful for cutting sections of the cuticle with the 

 epidermal cells adhering to it. 



LITERATURE 



Steedman H. F., 1947, Quart. J. microsc. Sei., 88: 123—33. 

 Wigglesworth V. В., 1953, Quart. J. microsc. Sei., 94: 93—112. 



— 1957a, Symp. Soc. exj). Biol., 11: 204—27. 



— 1957b, Proc. R. Soc. Lond., B, 147: 185—99. 



— 1959a, Quart. J. microsc. Sei. 100: 285 — 298. 



— 1959b, Quart. J. microsc. Sei. 100: 299—313. 



— 1959c, Quart. J. microsc. Sei. 100: 315—320. 



РЕЗЮМЕ 



Предполагается, что фиF^caция тканей четырехокисью осмия, т. е. осмиевой кисло- 

 той, оснопывается главным образом на окислительном проникновении ослгия в ориенти- 

 рованные цепи ненасыщенных жирных кислот. Этим путем осаждаются липоидные обо- 



43 



