DEVELOPMENT OF SPERMATOBIUM. 5 



never be melted, but the parafRne dissolved in pure tur- 

 pentine or xylol. 



When the latter is at last removed by alcohol the slides 

 are stained by a saturated solution of orange G. in 33 

 per cent, alcohol. The stain should be left on only a few 

 seconds, then immediately washed off in 95 per cent, al- 

 cohol. If too darkly stained wash gradually off with 

 weaker alcohol until the proper tint has been found. It 

 is better not to have the shade too bright yellow. Pure 

 water will wash out all of the stain. 



If it is found that nuclei of the hosts are not sufficiently 

 brightly or darkly stained by the h^matoxylon, the slide 

 may be again stained by a weak solution of Ehrlich's am- 

 monia h^matoxylon, under the microscope. Clear with 

 oil of bergamot, mount in gum-thus in xylol. Such sec- 

 tions give exceedingly good images. The nuclei of the 

 hosts were stained by the hasmatoxylon, while the nuclei 

 of the protozoa were stained by the orange and well dif- 

 ferentiated. The nucleoli wei*e nearly always stained 

 deep yellow, while the other part of the nucleus was 

 lighter; chromosomes and microsomes in the nuclei were 

 always stained very dark brown. The cell plasma of the 

 protozoa were stained lightly by the hsematoxylon. A 

 prolonged staining with only haematoxylon would stain 

 the protozoa nuclei, but such prepared sections did never 

 show the elements and structure of these nuclei. 



I will also here call the attention to the very great ad- 

 vantages of gum-thus in xylol as a mounting medium, it 

 giving images far superior to those by Canada balsam or 

 damar. 



IMMATURE INTRACELLULAR STAGES. Fig. la, h, C. 



The youngest stages of Spermatobium which I have 

 been able to observe are seen in the spermatogonmm, or 

 the mother sperm cell after it has dropped from the testis 



