1888.] MICROSCOPICAL JOURNAL. 27 



The author recommends the extract of logwood, which can be obtained 

 from any druggist, in place of hcematoxylin crystals, for making Weigert's 

 staining fluid for the central nervous system. He makes a solution of x part 

 of the extract of logwood in a mixture of 90 parts of water and 10 parts of 

 alcohol ; filters and adds to the filtrate 8 drops of a saturated solution, in 

 water, of lithium carbonate. Sections of tissues that have been treated as 

 described by Weigert are placed in this fluid for 18 to 34 hours at the room 

 tempei^ature. They are then decolorized in the borax-potassium ferricyanide 

 solution and mounted in the usual way. 



Francotte, P.* — A. 5 gms. of the extract of logwood are macerated in 

 9o"o alcohol ; i gm. of alum is dissolved in 300 c.c. of distilled water. For 

 staining add to a small dish full of the alum solution the alcoholic solution of 

 logwood, di^op by drop, until a blue violet color is obtained ; filter. 



B. Boil 15 gms. of logwood chips in 1,000 c.c. of water for several hours. 

 Then strain through linen, and afterwards filter through paper. Evaporate 

 the filtrate to dryness ; dissolve the residue in 50 c.c. of 9o"o alcohol ; allow 

 it to stand for several days and, finally, filter. For staining add this fluid, 

 drop by drop, to a i to 300 solution of alum in water, until a blue violet color 

 is obtained. , 



3. MOUNTING. 



Weigert, C. — Presei-vation of sections without the application of cover- 

 glasses. t 



By employing the carbolic acid-xylol mixturej for clearing, the use of a 

 cover-glass in mounting can be done awav with. The sections, after being 

 placed on a slide, are dried with filter paper, after the manner one would use 

 a blotter for ink. A layer of photographic negative varnish is then flowed 

 over the section and allowed to dry. This takes place quickly, but may be 

 hastened by gently heating the slide. This latter procedure must always be 

 employed when the sections become cloudy, due to the absorption of mois- 

 ture. After the first layer of varnish has become dry, a second layer is flowed 

 on, allowed to dry, and so on until after drying the sections become glazed. 



REPORTS OF RECENT ARTICLES. 



Origin of the excretory system of the earthworm, — Prof. E. B. 

 Wilson§ has called attention to the remarkable similarity between the devel- 

 opment of the nephridia and the origin of the excretory system in vertebrates. 

 Germ bands arise as in Clepsine ending behind in 8 large cells, by whose 

 continued division the bands increase in length ; of these, two are mesoblasts 

 (giving rise to the dissepiments, muscles and vessels) , two are neuroblasts 

 (giving rise to the excretory organs), the fate of the remaining two being un- 

 certain. The rows produced from the nephroblasts and the nephridial rows 

 produce in each somite a pair of solid outgrowths from which the nephridium 

 is eventually formed. Thus the nephridia arise as metameric growth from a 

 solid cord of cells, and is thus essentially similar to mode of origin of the ver- 

 tebrate, head kidney or pronephros. 



The nephroblast, when traced back to its origin, is demonstrated to be on 

 an ectoblastic cell only later, larger than the rest, and imbedded in them, and 



*Manuel de Technique Microscopique, 1887, p. 221. 



tZeitsch. f. Wiss. Mikros. Bd, iv, 1887, p. 209. 



tXylol 3 parts, acid carbolic i part. All water must be removed from this mixture by adding an excess of an- 

 hydrous cupric sulphate, prepared by healing the powdered crystals at a temperature of 100 C. until a white pow- 

 der is obtained ( H^eigert, Zeitsch /. Wiss. Mikros. Bd. Hi, iSSb, p. 4S0). 



§Proc. Acad. Nat. Sci. 1887, p. 49. 



