818 SUMMARY OF CURRENT RESEARCHES RELATING TO 



very effective for differentiating, for the nuclei of wandering leucocytes 

 and for the mitoses in epithelia. 



Hardening and Staining Plate-cultivations.* — Dr. E. Jacobi 

 hardens and stuius plate-cultivatiuns by putting the plates in flat vessels 

 and poui'iug over tbem a 1 per cent, solution of bichromate of potash, 

 which is allowed to act for three days in the light. If the thin gelatin 

 layer docs not detach itself it can bo easily removed with a knife. Then 

 follows twenty-four hours' soaking in water and afterwards hardening in 

 50 per cent, and 70 per cent, spirit. From this small lueccs of tho 

 gelatin, which arc treated just like sections, are stained with LofMer's 

 alkaline methyleu-blue and afterwards washed in very dilute acetic acid, 

 then placed in absolute alcohol, removed to tlie slide, where they are 

 cleared up in xylol or in turpentine oil, and then mounted in Canada 

 balsam. A leaden weight placed over the cover-glass serves to keep tho 

 specimen flat. Aniliu-water-safranin or Gram's method may be used 

 fur staining. Experiments with agar plates were xinsuccessful. Photo- 

 grams obtained from these specimens coloured red or blue, tho latter 

 from orthoehromatic plates, were satisfactory. 



Injection Mass for the Vessels of the Spleen.f — Dr. H. Hoy or 

 prepares a mass for injecting the vessels of the spleen in the following 

 manner: — 5 grm. of Berlin blue made up with oil (obtained from artists' 

 colourmen in zinc tubes) are rubbed up in a mortar with 5 grm. of in- 

 spissated linseed oil. To this are then gradually added about 30 grams 

 of some essential oil which is easily soluble in alcohol and has little 

 action on the tissues round about the vessels (e. g. oil of lavender, 

 fennel, thyme, rosemary) until a syrupy fluid is produced. It is then 

 poured into a well-stoppered glass vessel and allowed to stand for 

 twenty-four hours, when the supernatant fluid is poured off from the 

 sediment. Tliis blue fluid may tlien be preserved for an indefinite time, 

 but if it has stood for a few days it is necessary to shake it uj) before 

 usin'' it. This must also be done if other than blue pigments be used, 

 for example, chrome yellow, with which very satisfactory results arc 

 obtainable, the splenic capillaries appearing greyish-yellow by trans- 

 mitted, bright yellow with reflected light. 



The cannula is best filled with the injection mass by pouring the 

 latter in at the end. Injection of the spleen must be carried out very 

 slowly and at a very low pressure, and should be suspended when the 

 surface arteries become visibly coloured, and if the venous side be in- 

 jected when the whole organ shows the stain and before any actual 

 swellin" is observable. The preparation is then placed for twenty-four 

 hours in strong spirit or absolute alcohol in order to dissolve the essen- 

 tial oil and to precipitate the pigment on the inner surface of the walls of 

 the vessels. The organ may then be sectioned, stained, and mounted in 

 the usual way. 



This mass may be used for any other organ or tissue difiicult of 

 injection, as, for example, the marrow of bone. 



Injection with Indian Ink.| — Truf. K. Taguehi recommends, from 

 nine years' experience, the use of Indian or Chinese ink for cold 

 injections. The colouring matter is not affected by light or chemical 



* CcLtralbl. f. Bakteriol. u. Paraaitenk., iii. (188S) pp. 5.3G-8. 



t Iiiteriiat. Mouatsschr. f. Anat. u. Physiol., iv. (181S7) pp. 'Sil-hJ. 



X Arch. f. :\likr. Auat., xxxi. (1888) pp. 5G5-7 (1 pi.). 



