ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 475 



methyl-chloride in ethyl-chloride, having its boiling-point at 4° C. 

 When an object is exposed to a spray of anaesthol it very quickly 

 becomes frozen. Alcohol-hardened preparations should be placed for 

 a few hours, and fresh preparations for a few minutes, in formalin 

 before being frozen. 



Neuhaus, E. — Beitrag aur mikroskopischen Technik. 



[On the value of the freezing method, and on the superiority of ethyl chloride 

 as a freezing agent over ether.] 



Deutsche Med. WocJienschr., xxix. (1903) pp. 569-70. 



Bauuk y Cajal, S. — Unconsejo utilpara evitar los inconvenientes de la frabilidad 



y arrollamiento de los cortes en los preparados de Golgi y Marchi. (Device for 



obviating the brittleness and curling up of sections prepared by the Golgi and 



Marchi methods.) Trabajos lab. investigation biol. Madrid. 



ii. (1903) pp. 99-100. 



C4) Staining: and Injecting-. 



Concretions in Acetic-methyl-green. * — E. Andre calls attention to 

 the concretions which form in acetic-methyl-green, and points out that 

 their presence may give rise to some confusion, as they present the 

 appearance of organised bodies. They look something like starch- 

 grains, are concentrically laminated, are liable to linear fracture, are 

 round, ovoid, or occasionally of irregular shape. They begin to deposit 

 themselves in from 2 to 3 months ; at first are very small, but eventually 

 may attain a considerable size. They are easily dissolved by alkalis, 

 are not attacked by weak acids, and are coloured yellow by iodopotassic 

 iodide. 



Haematem and Hsemalum.t — P. Mayer writes that for some time 

 past he has made henialum directly from hematoxylin by oxidation 

 with sodium iodate, NaI0 3 , and that he has recently prepared haematem 

 in a similar way. " For the complete conversion of hematoxylin into 

 hasmatein, nine parts of the former to two of the latter would suffice ; 

 but in order to avoid too strong oxidation it is advisable to mix them 

 in the proportion of 10 to 2. 



One gramme of hematoxylin is dissolved in 10 c.cm. of distilled 

 water by boiling ; to the hot solution is added ' 2 grm. of sodium 

 iodate dissolved in about 2 c.cm. of water. The mixture is well shaken 

 and then cooled by placing the vessel in cold water. 



The hasmatein comes down as minute spherules or as microscopic 

 crystals. The deposit is placed on a filter and washed with cold water 

 to get rid of any sodium iodide. The haematei'n is then dried at room 

 temperature or with moderate heat. 



To make haemalum, 1 grm. of hematoxylin is dissolved in water 

 by boiling. The solution is made up to 1 litre with water; 0*2 grm. 

 sodium iodate and 50 grm. alum are added and allowed to dissolve at 

 ordinary temperature. When quite dissolved the mixture is filtered, 

 and is then ready for use. 



After a lapse of time hasmalum becomes liable to the formation of 

 scum on the surface, and a sediment. These may be avoided by the 

 addition of both chloral-hydrate and citric acid ; of the former, a 



* Zeitschr. wise. Mikr, xx. (1904) p. 412. + Tom. cit., pp. 409-11. 



