ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 429 



finely granular and auisotropous " intermediate disk " [Zwischen- 

 scheihe) which is devoid of the terminal membranes ascribed to it by 

 Merkel ; and (2) the anisotropous "transverse disk" [Querscheihe), 

 which is in two halves. Starting with these views as to muscle at rest, 

 Dr. R. Nikolaides applied a strong induction current to the sartorius of 

 the frog and. fixed the muscle by alcohol or osmic acid in the state of 

 maximal tetanic contraction. In a second series of experiments the 

 muscle was fixed at a stage before the maximum of contraction was 

 reached. Microscopic study of preparations so made showed that the 

 phenomena of contraction fell into two series. " First, the transverse 

 disk, which is the essential element, becomes broader and shorter, and 

 at the same time somewhat convex. Next, the shortening of the trans- 

 verse disks aj)proximates them one to the other, and, in strong con- 

 tractions, during this approximation, the fluid isotropous substance is 

 forced mechanically into the anisotropous portions, thereby causing 

 the thickening of the latter, and the lateral convexity of the sarco- 

 lemma. As for the intermediate and middle disks (Zwischen- and 

 Mittehcheibe), they have only a passive part to play in the phenomena 

 of contraction. They are the fixed points round which the above 

 phenomena take place. 



Hair Microscopically examined and Medico-legally considered.* 

 — Dr. W. J. Lewis draws attention to the importance in legal cases 

 (when it is often impossible to determine whether certain blood-stains 

 are human or animal) of the evidence to be derived from a micro- 

 scopic study of the hairs or textile fabrics of one sort or another 

 generally found entangled with the blood-stains on a weapon that 

 has been used in a murderous assault. He illustrates the value of 

 suck evidence by reference to actual cases, and points out the differ- 

 ences between human and animal hair, and the distinguishing features 

 of hair from those of the more common filaments which may be 

 mistaken for it, such as the finer fibres of jute, linen, silk, and cotton. 

 The characteristic distinctions which exist between human and animal 

 hair are briefly indicated under four heads, viz. (1) The relative 

 proportions of the cortical and medullary structures. (2) The size, 

 shape, and arrangement of the medullary cells. (3) The size, shape, 

 and arrangement of the superficial cortical cells. (4) The size and 

 shape of the hair-shaft. 



New Organic Spectra.f — Dr. C. A. MacMunn describes some 

 new absorption-spectra detected by means of the microspectroscope 

 without the aid of any reagent. Myohsematin gives three bands. 

 It has been detected in the heart-muscles of every vertebrate animal 

 examined, and in some voluntary muscles of both Vertebrata and In- 

 vertebrata. It has been got out of the muscle by digesting in pepsine 

 solution and out of the frozen heart-muscle of rabbits by pressing out 

 the plasma, in which it probably occurs like muscle-h£emoglobin, 



Histohsematin is the name given by Dr. MacMunn to a class of 



• Pioc. Amer. Roc. Micr. 7th Ann. Meeting, 1884, pp. 59-68 (2 pis.), 

 t Proc. Physiol. Soc, 1884, No. iv. See Nature, xxxi. (1885) pp. 326-7 

 (1 fig-). 



