MICROSCOPICAL TECHNIQUE. 421 



minence. . . . The epidermal glands of the second kind . . . are 

 nearly spherical, and have an average diameter of from i8 to 25 

 micromillimetres. They do not appear to have been recognised 

 by previous observers. Some of these lie in the deeper part of the 

 epidermis, but much the greater number and the larger ones occur 

 near the surface, where many of them are open. They stain 

 deeply with Kleinenberg's and with Delafield's hsematoxylin, but 

 in all other stains used, even in other haematoxylin dyes^ the nuclei 

 alone are coloured, and in this condition they can be distinguished 

 from small glands of the first kind only by very careful observation. 

 This probably accounts for their having been overlooked hereto- 

 fore. In Kleinenberg's haematoxylin the whole gland takes a blue 

 tint, while the wall presents a reticulated appearance due to an 

 irregular network of lines of a much deeper blue colour. . . 

 Haematoxylin has long been known to stain mucus deeply. Hover 

 ('90) found that basic stains are those which chiefly affect mucin, 

 and Delafield's (alum) gave characteristic deep blue stains to these 

 glands; Boehmer's (alum) and EhrHch's (acid), on the other hand, 

 gave pure nuclear stains. Hoyer imputed certain failures of hsema- 

 toxylin stains to act in their normal manner to lack of ripeness, 

 and it is possible that this may be the reason for Boehmer's alum 

 haematoxylin not colouring the mucin in this case." 



Preserving and Examining Copepoda.^— As a preservative 

 fluid for Copepoda, Mr. J. C. Thompson finds that a mixture com- 

 posed of equal parts of alcohol, water, and glycerine, with i per cent. 

 of carbolic acid, is most useful. Specimens may be transferred 

 direct to it from sea water, and can be so preserved for any desired 

 period of time, to be mounted direct, without further preparation, 

 in either glycerine jelly or Farrant's medium. 



Mr. Thompson employs an exhaustive method for capturing 

 these organisms with the greatest advantage, particularly when 

 material, or dredged mud or sand, is kept a considerable time 

 before it is examined. The dredged material is washed through 

 a coarse sieve into a finely meshed silk bag, into which a running 

 stream of water from a tap is allowed to fall. By careful kneading 



* Revised Report on the Copepoda of Liverpool Bay, by J. C. Thompson, 

 pp. 4, 5 {Trans. Liverpool Biol. Soc, Vol. vii., 1893). 



