ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



11; 



yields an unsuspected insight into the physical and physiological nature 

 of colour, and is of importance as regards our conception of the mixing 

 of colour. The smallest particles of a pure colouring matter are not 

 only characterised by their colour, but probably also by distinctive form 

 and movements. It therefore follows that colouring matters may be 

 analysed by this method. The composite colours examined showed their 

 smallest component particles either lying alongside each other (physio- 

 logical mixture of colours), or were seen to consist of particles differing 

 in shape, movement, and colour from those of the components. This 

 condition has been proved by more recent researches — for example, on 

 a mixture of Prussian-blue and naphthol-yellow — to rise from the fact 

 that the particles of one component cluster around those of another, 

 forming, as it were, a kind of sheath. This covering, according to 

 Raehlmann, is formed by electro-magnetic action, minute negatively 

 charged particles collecting around those positively charged, or vice versa. 

 These composite particles may be again separated by the action of electro- 

 magnetism. 



Dowdy, S. E. — Amateur Microscopy. 



[A series of four excellent articles upon this subject, describing a stu lent's 

 Microscope, its apparatus, and the way to use it. The articles are well 

 worth the attention of those intending to purchase a student's Microscope, 

 as well as of those taking up the subject for the first time.] 



English Mechanic and World of Science, Ixxviii., Nos. 2003-11 



(.Sept. and Oct. 1908). 



B. Technique.* 

 (1) Collecting Objects, including: Culture Processes. 



Wright's Collecting Bottle.f — This 



(fig. 17) contains an improvement by the 



introduction of an extremely rapid siphon, 



which is covered with a cylinder of very 



fine silk, thus preventing the escape of 



the smallest rotifer during the drawing off 



•of the superfluous water. At the same 



time the fabric permits the water to be 



drawn off almost as quickly as it is poured 



into the bottle. This apparatus will be 



found invaluable to those collecting pond 



life, as gallons of water can be rapidly 



drawn off by means of the siphon without 



sacrificing a single insect. A cork bung 



with boxwood top is supplied to the bottle, 



to save the loss of material collected. ^ 



Fig. 17. 



• This subdivision contains (1) Collecting Objects, including Culture Pro- 

 cesses; (2, Preparing Objects; (3) Cutting, including Imbedding and Microtomes ; 

 (4) Staining and Injecting ; (5) Mounting, including slides, preservative fluids, &c. ; 

 (6) Miscellaneous. 



t J- Swift & Son's Catalogue, Loudon, 1901, p. 42. 



I 2 



