ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 51 



of the sarcolemma sheaths. These " myoplasts " are observed in the tissue 

 of the external perimysium, chiefly among the muscle-bundles. As to their 

 origin, they may be derived from the elements of the osteogenic layer of 

 the periosteum, or perhaps from the so-called formative or plasmatic cells. 

 (3) Among the tendinous strands and in the tissue of the external peri- 

 mysium, very thin (1-2 /ji) muscle-fibrils are observed. Their origin from 

 the modification of the above myoplasts is described. The young fibre has 

 a sheath of sarcolemma, and this seems capable of growth. The muscular 

 fibre grows at either pole by means of new myoplasty, which become 

 terminally connected with the muscle-fibrils. (4) This account of the origin 

 of muscle-fibres confirms physiologically the correctness of the morpho- 

 logical division of fibres into fibrils. (5) The author believes that the 

 regeneration of destroyed muscle is also effected through myoplasts. 

 (6) Beside the normal fibres, he observed sarcolemma sheaths filled with an 

 unstriated, more or less opaque mass. The mass contained round or oval 

 elements, and one nucleus, or sometimes two. The muscular substance 

 was only represented by the slightest traces. These elements correspond 

 to the " Muskelzellenschlauche " of Waldeyer or to the " Wanderzellen- 

 schlauche " of Erbkam. 



Seeking to discover the nature of these peculiar sarcolemma sheaths, 

 the author proceeded to follow a method recommended by Kachmanmow. 

 The limb of a young animal was ligatured for 10-12 hours by means of an 

 indiarubber band. In animals killed within 24 hours after the removal of 

 the ligature, it was seen that the myoplasts nearest the end of an adult fibre 

 had not exhibited the modifications which, as above noted, serve for the 

 increase of the muscle substance. On the contrary, the change in their 

 nutritive relations brought about by the pressure had induced peculiar 

 transformations. The nucleus had disappeared, the protoplasm was granular 

 and had divided into five or six masses. The author believes that these 

 myoplasts destroy the muscle, penetrating into the sarcolemma sheath and 

 into the mass of the fibre, and in the abundant mitrition proliferating 

 rapidly. (7) The " Muskelzellenschlaucbe " and " Wanderzellenschlauche " 

 of other authors are these " myoplasts." 



y. General.* 



Colour-sense.f — Herr Tiebe gives a useful historical account of the 

 more important researches on the perception of colour and brightness 

 by animals. He devotes most attention to the recent researches of Prof. 

 Graber, who demonstrated over a wide series of forms sensitiveness to 

 differences of colour and brightness. 



Influence of Electric Currents on Tadpoles.^ — Herr L. Hermann has 

 continued his curious experiments on the behaviour of tadpoles in a vessel 

 through which an electric current was allowed to pass. They dispose 

 themselves in such circumstances with their head towards the anode. He 

 proved that this depended on the nervous rather than upon the muscular 

 system, and was only exhibited, for instance, by portions of tadpoles con- 

 taining part of the spinal cord. The experiments were varied in different 

 ways, e. g. by inserting one of the electrodes in the immediate neighbour- 

 hood of head or tail. The result was always the same, that the ascending 

 current produced lively movements and unrest, while the descending 



* This secfion is limited to papers which, while relating to Vertebrata, have a direct 

 or indirect bearing on Invertebrata al.so. 



t Biol. Centralbl., vi. (1886) pp. 489-503. 



I Arch. f. d. gesammt. Physiol. (Pfliiger), xxxiz. (18S6) pp. 414-9. 



E 2 



