INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 1031 



The method is especially good for the yellow plasmodium, as the 

 colour is precisely that of the picric acid solution. If white Plas- 

 modium is to be mounted, it should be soaked in 2.5 per cent, alcohol, 

 to remove the yellow colour of the picric acid, before anhydrating it 

 with strong alcohol. Experiments have not been tried with plasmo- 

 dium of purple and other colours to determine successful methods 

 of preservation, but some slight modification of the above is confi- 

 dently expected to succeed. 



Preparation of Green Algae.*— Last summer Prof. 0. Nordstedt 

 collected at Jonkoping the rare, and in many respects interesting, 

 alga, SphcBroploea annulina. This alga has the chlorophyll in the 

 sterile cellules arranged in transversal bands or rings. As he tried 

 to dry them, he found that the rings were destroyed by getting dry. 

 He repeatedly tried to obtain good microscopical preparations by using 

 *' liquor HantzschifB," as well as acetate of potassium ; but when 

 unsuccessful, he applied warmth. He put a small bottle, containing 

 the alga in water, on a black object, and exposed it to strong sunlight 

 for a couple of hours. When the alga afterwards was dried, the rings 

 proved to be pretty well preserved ; when afterwards heated by a 

 spirit lamp, the thermometer indicated that the rings when boiled 



h minute at 35°-40° Ccls. Did not keep, or were very badly preserved. 

 Wiien boiled 5-10 minutes! 



at 45° Cels., § minute at > The rings kept very well. 



50°-98°Cel3 ) 



10 minutes at GO- Cels., j"^'?^ ""?' Tf ^T'^'lf ^'T *V "^•'?' 

 2 minutes at 98° Cels. j tiie^'celTule ° ''^ " ''^"""''"^^ 



It appears to be most convenient for the purpose to use 40^-50° Cels. 

 during about two minutes. 



In the Spirogyra tlie chlorophyll-bands, when the plant was boiled, 

 also kept tolerably well ; ho, therefore, has often applied heat in pre- 

 paring them. The different species seem to require different degrees 

 of heat. 



Slides from the Naples Zoological Station. — A provisional 

 priced catalogue of the microscopical preparations issued by the 

 Zoological Station at Naples t has now been published.f It includes 

 4 different preparations of Protozoa, 33 of Cadenterata, 49 of Echino- 

 dermata, 33 of Vermes, 57 of Arthropoda, 54 of Mollusca, and 193 of 

 Vertobrata. 



The list is prefaced by an explanatory note by Dr. A. Dohrn, tho 

 Director of the Station, in which he points out that tho microscopical 

 preparations which have liitlicrto been sold " have only in rare cases a 

 true 8ci(!ntitic value. For tliis they must not only be prepared by hands 

 well skilled in the t(;i-lmicul processes, but thero must also bo tho 

 understanding of scientific prol)lenis and points of view," so that tho 

 preparations may exhibit just those jiuints which ai-o of importance 



* 'Grovilloa,' ix. (ISSO) pp. .S7-8 (from 'I3ot. Notiser'). 



t See this Journal, nntc, p. 700. 



X ' MT. Zool. Stat. Nenpel,' ii. (1880) pp. 238-53. 



