ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 499 



developed by using the smallest aperture of the condenser, but that they 

 instantly vanish when the light is restored. 



There can be very little doubt that Mr. Smith is right in his criti- 

 cism, and that it is Dr. Pigott's defective methods of manipulation that 

 have led him astray in this matter. 



New Appearances in Podura Scale.* — Mr. T. F. Smith calls atten- 

 tion to what he considers to be a new appearance of the Podura scale not 

 yet recorded. In place of the optician's appearance of the scale, with 

 the exclamation marks, blue or red, according to the corrections of the 

 glass, and with a light streak in the middle, more or less extended as 

 the aperture is larger or smaller, the usual markings had vanished, and 

 in their stead " the whole scale was studded with very slender spines 

 with round heads, and the pointed ends stuck into the scale like a lot of 

 pins stuck loosely and anyhow into a paper, and instead of being blue 

 or red were a pure white." At first he thought there were two sides to 

 the scale, and that this was the wrong one, but he found that the scale 

 was tight against the cover, and that all the scales so placed had the 

 same aj>pearance. 



Since then he has examined many scales on sevoral slides, and is 

 " now strongly of opinion that the note of exclamation markings are 

 spurious, and that the light streak is the true appearance, which has 

 hitherto been seen with the darker outline on each from taking too deep 

 a focus. It is a well-known fact that an oil-immersion objective works 

 only with its full aperture when an object mounted dry is well on the 

 cover, and this in itself should be sufficient evidence that the appearance 

 the object presents, under these circumstances, is the truer one. Then, 

 again, the pin-like looking spines are not more than half the diameter of 

 the exclamation marks, and the image is always at its smallest when in 

 focus ; never larger." Another fact which guides the author in his 

 estimation of the structure is the observation of a hair with small pro- 

 jecting spines. "Here was structure of which there could be no doubt, 

 and the same point of the correction-collar that gave the sharpest image 

 of this hair gave also the sharpest image of the spines on the scale. 

 Still another proof. To bring the note of exclamation marks out well 

 requires a deal of management of the light, and they are best seen with 

 the smallest apertures of the condenser ; but no amount of light will 

 obliterate the new ones or prevent them from standing out sharply from 

 the general blaze." 



" New Glass just made in Sweden."— We have received from a con- 

 siderable number of correspondents cuttings from various newspapers 

 describing this " new glass." As will be seen it is a revival of the 

 paragraphs to which we called attention in the last volume of this 

 Journal, pp. 155 and 321. What is the cause of this recrudescence 

 we do not at all know, but it has apparently been disseminated all over 

 England, as our cuttings come from London papers, local country 

 papers, religious papers, &c. 



The paragraphs are the most outrageous piece of rubbish ever pub- 

 lished, and while of course editors can't be expected to know everything, 

 they might surely get to know enough to avoid putting in such asinine 

 statements as these. 



" Perhaps the most wonderful thing that has been discovered of late 



* Journ. Quek. Micr. Club, iii. (1888) pp. 203-4. 



2 M 2 



