422 Progress in Science. [J u ty> 



Mr. E. Ray Lankester describes the spedtrum of Stentorin, the* colouring 

 matter of Stentor cczrtdius.* It has two bands, the stronger in the red on the 

 lower side of the C line ; its centre is nearer the blue than the red band of 

 fresh chlorophyll. The second band in the green lies somewhat to the blue 

 side of the lower band of fresh blood. Light which has been passed through 

 the thickness of only a single Stentor (which cannot be more than a few 

 thousandths of an inch) is sufficiently affected to show the bands quite 

 sharply. This affords an instance of the value of the micro-spectroscope in 

 cases where only a small amount of coloured material is procurable. 



In a paper on a new species of Callidina, read before the Royal Microscopical 

 Society,! Mr. H. Davis. F.R.M.S, gives the result of his experiments on the 

 desiccation of this and other rotifers. He has, in common with Pouchet and 

 other observers, arrived at the conclusion that rotifers when completely dried 

 do not revive upon being placed in water. Those which have recovered, and 

 some have done so after gradually heating to 200 1 F. in an oven, and 

 being kept for a week under an exhausted receiver with sulphuric acid, have 

 been protected, according to Mr. Davis's observations, by a gelatinous secre- 

 tion which dries over them into a hard thin shell, and effectually secures them 

 from the most complete desiccation the chemist can effect. That such a coating 

 is an effectual protection was demonstrated by the production at the meeting 

 of some grapes coated with gelatine, which had been with sulphuric acid in 

 an exhausted receiver for seven days and nights, and were still perfectly fresh 

 and juicy, while some from the same bunch put by in a cupboard without pro- 

 tection were shrivelled and mouldy. 



The lens ruled in squares t by Mr. Ackland for the purpose of making 

 drawings of objects under the microscope has, upon trial, proved successful, 

 the definition being very little affected by it. The markings of the scale of 

 Lepidocyrtus curvicollis ("the test Podura") were very well seen under an 

 eighth of Powell and Lealand's new make, magnifying with the eye-piece 

 employed about 800 diameters, scarcely any mischief was done excepting the 

 production of a little colour, the "I markings" were clear enough to permit of 

 a good drawing being made. A convenient size for the squares is o - o5 inch. 

 The drawings are made on ruled paper, several sizes of which, under the name 

 of " sectional paper," are manufactured by Messrs. Letts. Although originally 

 intended for the use of architects, for enlarging and reducing it will be found 

 equally available for microscopical purposes. 



The well-known large microscope stand of Mr. Thomas Ross has been 

 remodelled and improved by Mr. F. H. Wenham. The base consists of a single 

 casting, the claws of which are well spread, and give a very firm support to 

 the movable portions of the instrument. The chief variation from the 

 former construction consists in the adoption of the " Jackson Model,'' so 

 strongly advocated by Dr. Carpenter, \ and respecting the rigidity of which 

 there cannot be the least doubt. This is so adapted as not to interfere with 

 the elaborate stage mechanism, which works as freely as in the old form. The 

 " doze-tail groove " in the limb is supplemented in its action by a broad flange 

 on the bar carrying the body, which works in close contact with a corre- 

 sponding plate on the limb, and prevents any chance of a rocking motion 

 taking place. The fine adjustment, as will be seen by the woodcut, is placed 

 in an extremely convenient position, and can easily be reached from either 

 side without the hand being removed from the milled head working the rack 

 motion. The stage and sub-stage arrangements are the same as those in the 

 older form, and need no especial mention. The stand, as now improved, is to 

 be particularly recommended for its great strength and consequent capability 

 of standing hard wear, a quality of considerable importance to the working 

 microscopist. The stiffness of its framing will also recommend it to those 

 who are compelled to carry on high power observations in unquiet situations 



* Quart. Journ. Micros. Soc, April, 1873, p. 140. 



t Month. Micros. Journ., vol. ix., p. 201. 



i Quart. Journ. Science, p. 277. 



? Monthly Micros. Journ., vol. iii., p. 183. 



