94 THE MICROSCOPE. 



used for this purpose, and showing other interesting points 

 of structure. 



The warty Newt is in a state of great activity early in 

 spring. It is common in ponds and large ditches, where it 

 feeds upon the tadpole of the common Frog. The male 

 and female Newt are nearly the same in appearance during 

 winter; but in spring a beautifully-cut crest rises from 

 the back of the male, which is highly ornamental. The 

 egg is very slightly tinged with buff, and is surrounded by 

 a substance resembling the white of a common egg, in 

 which it keeps continually whirling round. It goes 

 through several changes from the egg before it becomes a 

 perfect animal; for a considerable time it remains in 

 a tadpole state, very like the common Frog. 



Before we conclude, we beg to call the attention of 

 our readers to the beautiful experiments of Mr. John 

 Gorham, 1 as illustrating the wonderful magnifying power 

 of the human eye. The fact itself is one of great interest 

 to the microscopist, who has hitherto almost exclusively 

 availed himself of the optician's aid in his examinations of 

 minute bodies. 



We are only able to notice the results arrived at by this 

 able investigator, which are as follows : " That when small 

 bodies are brought very near to the eye, their images are 

 magnified, just as images of larger objects, when seen at a 

 distance, are diminished, and by the same law. The 

 apparent magnitude of objects depends on their visual 

 angle. The visual angle, for short distances, may be well 

 illustrated by employing a small circular disc of light. 

 This minute circular disc of light is procured by per- 

 forating a card with a needle. A sewing-needle, of the 

 size marked No. 7, produces an aperture about the one- 

 fortieth of an inch in diameter. In order to examine the 

 light which is transmitted through such an aperture, all 

 extraneous rays should be excluded ; hence the plane in 

 which the opening is made should be placed at the end of 

 a tube. The pencil of light admitted through an opening 

 of this kind, held within an inch or so of the eye, consists 

 of rapidly-diverging rays falling upon the cornea. Some 

 of these are entirely lost, others are intercepted by the iris, 



(1) Quarterly Journal of Microscopical Science, October 1854. 



