482 NEUROFIBRILS 



Formula 6, A. Fix for twenty-four hours in 10 per cent. 

 chloral hydrate, wash for six hours and put direct into the silver. 

 Stove for four days. Results similar to those of Formula 1. 

 Medullated fibres well stained. 



Formula 7. Fix for twenty-four hours in Merck's fibrolysine, 

 wash for six, put for twenty-four into 50 c.c. of alcohol with 5 

 drops of ammonia. The rest as by other formulae. 



Instead of fibrolysin, lysidine may be taken. 



1012. Application of Cajal's Methods to different Objects. 

 1. For the study of the evolution of neuroblasts and nerve-fibres 

 in very early embryos it is necessary to avoid fixing with formol, 

 or alcohol with an accelerator, or ammoniacal liquids. The best 

 formulae are 2 and 5 which are applicable to all vertebrates, but 

 preferably to embryos of birds and fishes. 



2. For late embryos and foetus of mammals. Besides the above 

 formulae, 3, 6 and alcohol with an accelerator. Best subjects, 

 embryos of chick from the fifth day, and of rabbit from the tenth 

 to the twelfth day ; or new-born birds, with ammoniacal alcohol, 

 or 5. 



3. For sympathetic ganglia. Formula 3, or pure alcohol, or 

 4 and 5. Best with man. Dog, cat, and rabbit give mostly 

 weak reactions. The visceral ganglia are the most difficult. 



4. Sensory ganglia. Formula 2 or 3. Easy. 



5. Cerebellum. For Purkinje cells, 1 or 3. For the baskets, 

 climbing fibres, and medium and small dendrites, 2 or its variants. 

 For terminal rosettes and collaterals of moss fibres and for the 

 plexuses of the granular layer, 4 or sometimes 5 or 6. For the 

 stellate cells of the molecule layer, 2 and 3. The best subject for 

 the latter is the dog. 



6. Cerebrum. In general, the same formulae as for the cere- 

 bellum, especially 1 for pyramids of young dogs and cats (of eight 

 to twenty days). In Formula 3 the proportion of ammonia 

 should be diminished. For fine plexuses, 4, 5, and 6. 



7. Spinal cord and bulb. All the formulae are applicable. 

 For neurofibrils of motor cells the best subject is the dog of four 

 to fifteen days, with Formula 3, with a large dose of ammonia 

 (10 drops) ; also the alcoholic fixatives with an accelerator. 

 For medullated fibres, large and small, 2 or 6. For buds of Held 

 and Auerbach and for fine plexuses, 4, 3, A, or 5. 



8. Ganglia of invertebrates. For the medicinal leech (not for 

 other leeches), 1, A. For Hcemopis, Aulostomum, Fontobdella 

 and Glossiphonia, 2 or, better, 3, with not more than 2 to 5 drops 

 of ammonia and 3 per cent, silver nitrate, stoving three or three 

 and a half days. For further details see Sanchez, Trab. Lab. 

 Invest. Biol., Madrid, vii, 1909, pp. 42—47. 



Lumbricus is generally refractory to Cajal's methods. Boule 

 {Le Nevraxe, x, 1908, p. 15) obtained good impregnations by 



