114 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



The myo-spectroscope is shown in Fig. 23. T' is a tube 12 cm. long 

 and 4 cm. in diameter, blackened internally, and closed at one end by 



Fig. 23. 



a diaphragm with a vertical slit/' half a millimetre in breadth. At 

 the other end is a stage plate with a central hole o (5 cm.). The 

 preparation of muscle is placed in the clips in front of the latter hole 

 and so that the axes of the muscular bundles are at right angles to 

 the slit/'. On looking through the hole, whilst the instrument is 

 directed to a light, spectra will be seen on the right or left of the slit. 



To observe the absorption-bands of haemoglobin, a second tube Tis 

 added to the instrument, sliding over T' and having a diaphragm with a 

 large vertical slit/" in which is placed a tube S containing a solution 

 of blood. Having first seen that the muscle gives a clear spectrum, 

 T with S is replaced and the two absorption-bands of haemoglobin 

 will be seen in the spectrum. 



As the spectrum produced by a grating is more extended according 

 as the lines of the grating are closer together, we are led to investigate 

 whether a muscle at the moment of contraction gives a wider spectrum 

 than when at rest. The lower tendon of the sartorius muscle of a frog 

 is separated from the tibia and the muscle stretched before a slit and 

 it will be seen that on slightly stretching the muscle, the spectrum 

 will be narrow and close to the slit. When the muscle is contracted 

 the converse phenomena are produced, and when it is excited by a 

 current and attains its maximum of contraction the width of the spectra 

 and their distance from the slit are much angmented. 



The muscles of different animals thus examined do not give 

 identical spectra. For example, those of the muscles of the frog are 

 broader than those of the white muscles of the rabbit in the ratio of 

 9 : 7. The transverse striation is therefore finer in the former case 

 than in the latter. 



Standard for Micrometry.* — The Philosophical Society of 

 Washington publishes the reply given by Dr. J. J. Woodward to the 

 committee of the Microscopical section of the Troy Scientific 

 Association who asked answers to the following questions : f — 

 " 1. Is it expedient at present to adopt a standard for micrometry? 



2. If so, should the English or the metric system be employed ? 



* Bull. Phil. Soc. Washington, iii. (1878-80) pp. 22-4 ; Smithsonian Misc. 

 Coll., XX. (1881). 



t See this Journal, ii. (1879) pp. 154-5. 



