ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 567 



haemoglobin shows that in the higher vertebrates there exists within the 

 corpuscle a substance analogous to albuminoid bodies, and which is able to 

 crystallize without the corpuscular form changing. The corpuscle is de- 

 colorized because the yellow substance separates from the other which is found 

 in the cortical portion, and crystallizes without leaving a trace of the nucleus. 



The normal form of the mammalian red corpuscle is not that of a bicon- 

 cave disc, as is usually believed, but this appearance is produced by altera- 

 tion of structure due to unsuitable conditions, mechanical violence, chemical 

 reagents, and the like. In his experiments Sig. Mosso used very dilute 

 solutions (sodium chloride 0*75 per cent., stained with methyl-violet 1 in 

 5000), alkaline eosin 1-2 per cent., NaCl 0-6 per cent., or methyl- 

 green 1 per cent. Except blood-serum, all other fluids were found to alter 

 more or less rapidly the red corpuscles, but contact with glass is stated to 

 be extremely damaging. For example, if a drop of blood squeezed out of 

 a pigeon's feather be treated with 2 per cent, eosin solution, and viewed 

 without contact, the nucleus will be found unstained. But if the same drop 

 be but lightly touched with a cover-glass, the corpuscles become altered, the 

 nuclei become red and swollen, the cortical jDart more pallid, as if the haemo- 

 globin had disappeared. This great susceptibility of change Sig. Mosso con- 

 siders to have been the cause of many errors, and these of such magnitude that 

 it is necessary to repeat the whole course of the histology of the blood, for every 

 ordinary method of examining blood destroys the cortical part of the corpuscle. 



Sig. Mosso concludes by alluding to the diflerences in the resistance of 

 red corpuscles. This resistance was measured roughly by means of • 3 per 

 cent, chloride of sodium solution, stained with methyl-violet 1 : 5000, and 

 more accurately by successive strengths of the chloride solution (0-76-0 '4 

 per cent.). These experiments are not yet fully completed, but it may 

 be stated that the resistance for any given species is very variable, and that 

 the corpuscles of birds are the most resistant. 



Nuclei of Striated Muscle-fibre in Necturus (Menobranchus) 

 lateralis.* — Mr. A. B. Macallum has obtained his best preparations of the 

 nuclei of Nedurus lateralis with gold chloride and formic acid ; many of 

 the isolated nuclei have on their surface furrows and striations ; the former 

 are probably due to the pressure exercised by the trabeculae of the muscular 

 reticulum ; this last appears to the author to be the true contractile element, 

 while the myosin shifts and accommodates itself. In some cases the 

 reticulum was not on, but in the nucleus, and in these cases no chromatin 

 or caryoplasma could be discovered. Mr. Macallum thinks with Carnoy 

 and Melland that the muscle reticulum is simply the modified cytoplasma, 

 the caryoplasma being derived from the latter. "When the caryoplasma is 

 modified as in some of the cells observed, the nuclei must be capable of 

 movement, or of contraction and extension ; the possession of a square- 

 meshed reticulum implies extension and contraction in definite directions — 

 the nucleus contracts with the muscle-fibre and extends with it again, yet 

 not passively. Where nuclei have part of their surface completely free 

 from furrows, we may sujjpose that part only of the nuclear body is sur- 

 rounded by the muscle substance, a part of it lying between the latter and 

 the sarcolemma. 



Variations in Wool.f — Dr. F. H. Bowman gives an interesting account 

 of variations observed in the structure of wool and other fibres. These 

 indicate a constant tendency to a reversion to a more primitive type, besides 

 illustrating the effects produced by the environment or by artificial selection 



' Quart. Journ. Micr. Sci., xxvii. (1887) pp. 461-6 (1 pi.), 

 t Proc. Roy. Soc. Edin., 1S87, pp. 6.57-72 (1 pi.). 



