MICROSCOPE. 



667 



different species, and even from the variety of 

 figures which one solution presents to view. 



Figs. 47, 48, 52. Crystalline figures of Common 

 Salt. A solution of common table salt presents, 

 in addition to the perfect crystals, a variety of 

 singular configurations. Fig. 47- resembles a cor- 

 alline formation, and is composed of a vast number 

 of small cubes irregularly disposed, which from 

 their extreme minuteness exhibit, under the most 

 powerful magnifiers, only an aggregation of shining 

 dots. Fig. 52 is a similar formation, except that 

 all the lines are parallel or at right angles to each 

 other. Fig. 48. is a more complicate configuration ; 

 the middle stem is first formed, and afterwards the 

 processes on each side branch out. This forma- 

 tion much resembles a crystallization of soda. 



Fig. 46. Crystals of Saliva. If a slip of glass 

 be wetted with the tongue, and afterwards sub- 

 mitted to a powerful amplifier, the gradual eva- 

 poration of the moisture will discover a crystalline 

 formation very much resembling Fig. 52. 



We advise those who may take an interest in 

 witnessing the astonishing process of crystalliza- 

 tion, as developed under the microscope to use 

 a compound instrument, which gives them exten- 

 sive field, and considerable power, yet enables 

 them to keep the object at some distance from the 

 lens, by which the evaporation of the solution is 

 less liable to condense upon the objective glass, 

 and disturb the observation. 



Figs. 50, 51. Snow Flakes An almost infinite 

 variety of form is observable in the minute crys- 

 tals of a snow flake ; the beautiful and complicate 

 figures they present are truly wonderful, and fully 

 reward the observer for the frequent disappoint- 

 ments he must suffer in attempting to bring them 

 effectively under the microscope. The specimens 

 shown in our engraving are copied from the delinea- 

 tions of other observers. 



Fig. 49. A Transverse Section of the Clematis. 

 The delicate structure of this object is shown 

 under a superficial power of 400. 



The remaining 17 figures, viz., from Fig. 53 to 

 Fig. 69, inclusive, refer to Infusoria. For these, 

 we have before noticed, we are indebted to Mr 

 Pritchard, who permits us to copy them from his 

 Natural History of Animalcules; from the same 

 talented and beautifully illustrated work we extract 

 so much as is necessary in the way of particular 

 description and general information. It will not 

 be out of place to notice here, that Mr Pritchard 

 has caused copies of his elaborate engravings to 

 be delicately and accurately coloured ; and we can 

 scarcely conceive a more valuable companion to 

 the microscope. 



The subjoined table exhibits the genera of the 

 Infusoria, the number of species included under 

 each genus, and the individuals selected for illus- 

 tration of special character. 



1. Monads. 



2. Proteus. 



3. Volvox. 



4. Enchelis, with the 



No. of Species 



Enchelis, with the") 

 Bacterium of Khren- > 33. 

 berg. J 



21. The Drop Monad. 65. 



3. The Melting Proteus. 66. 

 13. The Vegetable Volvox. 67. 



TheEgg-shaped Encholia. 61. 



5. Vibrio, including 

 Bacillaria, 

 Phytozoa, 

 Entozoa. 



C. Cyclidiura. 



7. Paramaecium. 



8. Kolpoda. 



9. Gonium. 



10. Bursaria. 



59. The Stick Vibrio. 



88. 



The azure Cyclidium. 62. 



Paramaecium chrysalis. 63. 



The Cuckoo Kolpoda. 64. 



The Breast-plate Gonium.69. 

 ( TUp little Swallow-like) ,.,, 

 I Bursaria. 



Genera. No. of Species. Individual*. Pi*. 



11. Cercaria. 25. The Green Cercaria. 59. 



12. Leucophrys. 28. TheBraceiet Leucophrys. 54. 



13. Trichoda. 91. Trichoda vulgaris. 55. 



14. Kerona. 14. Kerona pullaster. 50. 



15. Himantopus 7. Himantopus larva. 58. 



' irludin? ~ 



57. 



16. Vorticella, including " 



Polygastrica, > 70. Vorticella cyathini. 

 Rotatoria. ) 



17. Brachiouus. 22. Brachionus paesus. 53. 



It will be noticed that in stating the number of 

 species under each genus, we confine ourselves to 

 those figured and described by Mr Pritchard ; this 

 explanation is necessary, as in some genera the 

 species are more numerous in the arrangement of 

 other naturalists. 



Monads. "This genus of animalcules includes 

 the smallest forms in which a voluntary motion 

 has been observed, even under the most powerful 

 microscopes : this motion, until recently, appeared 

 to be the only property of life with which they 

 were endowed ; but the observations of Dr Ehren- 

 berg demonstrate an organization equally perfect, 

 with animated beings of much larger dimensions. 

 Their forms in general are simple, spherical, or 

 cylindrical masses, devoid of external members or 

 processes :* the mouth, which is with difficulty 

 discerned, is a simple orifice, not furnished with 

 cilia or hairs, (except in one or two species :) 

 they are colourless, and transparent as the clearest 

 crystal, yet can no internal organization be seen, 

 excepting that connected with their digestive 

 function, which consists of two or more globular 

 cavities or sacs, probably communicating with each 

 other by a tubular membrane, as in the larger 

 polygastric animalcules, but which in this genus is 

 too minute to be discerned ; indeed, the stomachs 

 or sacs themselves are only to be observed when 

 the animalcule is fed with particles of colouring 

 matter : the food on which they usually exist being 

 as pellucid as themselves, the cavities are invisible. 

 They increase by a spontaneous division of the 

 parent into two or more parts, and those parts, or 

 young, again divide when they have attained their 

 full size." 



" As subjects of observation they are principally 

 interesting from their minuteness, being as they are, 

 the very limit of man's acquaintance with animated 

 nature. Their diameters vary from 1 -24000th of 

 an inch to l-1200th, and consequently require a 

 very high magnifying power to discern. They are 

 numerous, and generally found congregating at the 

 surface, and around the decomposed matter of in- 

 fusions, either of vegetable or animal substances." 



Fig. 65. The Drop Monad. " This animalcule 

 is larger than the Atom Monad, and somewhat glo- 

 bular. On account of its size and transparency, its 

 digestive cavities can be much more distinctly ob- 

 served. It revolves about its longer axis, and in 

 swimming, that part which contains the coloured 

 particles follows the colourless part. Occasionally, 

 with attentive observation, currents in the water may 

 be seen about the fore-part or mouth ; it is there- 

 fore highly probable that it is furnished with ciliae 

 or hairs. Those found at Petersburgh, measured 

 from l-3000th to l-2300th of an inch in diameter : 

 they are represented in the group magnified 380 

 times. "f 



Proteus " "We now arrive at a larger genus of 



animalcules, whose habits are highly interesting 



* My observations on the mona punclum require a modifi- 

 cation of this part of the definition, or removal out of this 

 gonus. A. P 



t Mr Pritchard morely stains tho magnified diameter. 



