PROGRESS OF MICROSCOPICAL SCIENCE. 31 



culty. Also the examination of the fresh gland in iodine serum is of 

 great advantage. 



Br. Pigott on the Podura Scale. — Dr. Pigott, F.E.S., in conjunction 

 with Mr. E. B. Beaumont, F.E.S., has published his observations on 

 the structure of the Podura scale, in the ' Proceedings of the Royal 

 Society ' (in a recent number). He says, speaking for both authors, 

 that nothing in microscopic matters has ever afforded us such com- 

 plete satisfaction as the following result of a very fine definition, 

 accomplished by means of a Gundlach German xV^^^ immersion lens, 

 corrected by a new method, which Dr, Pigott at present delays pub- 

 lishing in the hope of further improvement, but which he is willing 

 to exhibit at his house. The idea conveyed by looking at the object 

 which is figured in the ' Proceedings' was, that two layers of spherules 

 (first detected by Mr. Beaumont within the tubes), like two confined 

 layers of small shot, had, by compression, been forced and largely 

 spread out into broader layers. It was thought also that detached 

 portions resembled long tubes or puckers filled with sjiherules exactly 

 fitting them. The spherules appeared perfectly spherical,. but some- 

 what unequal in size.- In the general flattened and extended surface 

 of the compressed and disintegrated scale the spherules aj)i)eared dark 

 blue or red, according to the slight change in the focal plane, aud in 

 a still lower plane white. In the adjoining uninjured scales long 

 strings of beads were seen, like necklaces of coral, here and there 

 sharply bordered with black lines, apparently denoting tubes of mem- 

 brane or puckers enclosing them like a tube. Between these strings 

 of spherules peeped forth others of a light orange-colour. The slide 

 was an old one and well known. The mass of the crushed scale 

 occupied a much broader space than any of the scales. 



Mr. Sorh'/s recent Researches in Vegetable Chromatulogy are of 

 great interest. They are published at very considerable length in 

 the ' Proceedings of the Royal Society,' and though not many of 

 them come within the rank of microscopy, yet they are of great 

 chemical and physical value. With regard to Fucoxanthine the 

 following remarks are made : — " This is the name I propose for the 

 principal colouring-matter of Fiici and other olive Algce. It may be 

 obtained in the manner already described, only that in order to sepa- 

 rate it from the chlorofucine, after separation of all the chlorophyll, a 

 few drops of ammonia should be added to the alcoholic solution, and 

 the whole diluted with an equal bulk of water. The bisulphide of 

 carbon is then precipitated with almost all the fucoxanthine, whilst 

 nearly the whole of the chlorofucine remains in the dilute alcohol. 

 As thus purified, fucoxanthine dissolved in bisulphide of carbon is of 

 a beautiful amber colour, and its spectrum shows two obscui'e absorp- 

 tion-bands, the position being intermediate between those of orange 

 xanthophyll and xanthophyll, so that a mixture of these gives nearly 

 the same spectrum. The difference, however, is completely proved by 

 other facts. The bands of fucoxanthine are much less raised by 

 alcohol and other liquids of high band-raising power than the bands 

 of those two kinds of xanthophyll, and it resists the action of light far 

 VOL. XI. D 



