lUlG SUMMARY OF CUUIiENT RKSEARCUE8 RELATING TO 



tiou and Position of the Oell-nuclous in Plants' Dr. G. Habcrlandt gives 

 tbo following now motliods. 



In order to control the growth of the root-liairs and to bo able to 

 measure their increase (it not being possible to mark these forms arti- 

 ficially), tlie germling was placed in the moist chamber on a slide, and 

 then fine dry rice-sturch was blown against the root-hairs and thereupon 

 the cover-glass imposed. The starch-granules adhere to the sticky 

 surface of the hairs and form marks i)laced at irregular intervals. The 

 mcasiu-ements were made under a low power by means of an ocular 

 micrometer. The experiments frequently fail because the tender sensi- 

 tive bail's very frequently stop growing after they have been marked. 

 Successes, however, were scored with Cucurhita Pejjo, Pisum sativum, 

 Polygonum Fagopijruin, Uelianthus annuus. 



For studying the cell-nucleus, Vaucheria filaments were cut in two, 

 and 20-30 minutes afterwards placed in a 1 per cent, chromic acid solu- 

 tion and the nuclei eventually stained with picrocarmine. For examining 

 the plasma-balls ejected by the wounded Vaucheria the plants were not 

 cut up in water, but in a 5-10 per cent, sugar solution, and cultivated 

 for three to seven days either in porcelain capsules or in hanging 

 drops. 



It may also be mentioned that the author repeatedly obtained good 

 results with picrocarmine, dilute methyl-green and acetic acid, and with 

 borax-carmine. Excellent i)reparations showing the lacteal vessels were 

 obtained by laying pieces of the epidermis in borax-carmine for several 

 to twenty -four hours, and after treating with hydrochloric acid-alcohol 

 examining in glycerin. The nuclei of Saprolegnia were brought out by 

 hardening in 1 per cent, chromic acid, carefully washing, and staining 

 with ha^matoxylin. Spores of Pertusaria were first treated with alcohol 

 and ether to remove the oil in the nuclei, then stained with picrocarmine 

 or logwood. 



Preparation of Fresh-water Algae.* — Dr. L. Klein proposes a 

 modification of the ordinary method of preparing fresh-water algjc for 

 microscoj^ic examination. The use of any fluids, such as glycerin or 

 potassium acetate, he has almost entirely abandoned, because of the time 

 required in their preparation to secure their permanency, and the danger 

 of injury to the cover-glasses in cleaning them. In those cases where a 

 fluid is necessary, as when a single minute object lies in water beneath 

 the cover-glass, he places a drop of 1 per cent, superosmic acid on the 

 margin of the cover-glasses, and, after ten or twelve minutes, potassium 

 acetate ; this is blown under the cover-glass by means of a very fine 

 glass tube. The hardening is effected by superosmic acid, and the 

 closing by Canada balsam. 



The solid substiince preferred by Dr. Klein is Kaiser's glycerin-jelly,t 

 viz. 1 part of very fine gelatin diluted with six parts of distilled water for 

 two hours, and 7 parts by weight of chemically pure glycerin then added. 

 To 100 gr. of this mixture 1 gr. of concentrated carbolic acid is added, 

 and the whole warmed fur ten minutes. In order to prevent shrivelling 

 up the algae must be hardened in sujierosmic acid before placing in the 

 glycerin-gelatin. 



For minute, and especially for unicellular algae, Dr. Klein uses not 



♦ Hedwigia, sxvii. (1S88) pp. 121-6. f See this Journal, 1887, p. 691. 



