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Trypanosoma lewisi 
how the staining is progressing. No general rules can be laid down 
because the Giemsa-solutions are often very irregular with regard to 
their power of staining. With these precautions I never observed the 
intensely stained structureless nuclei described by Minchin. It is 
evident that only with dried preparations one is able accurately to 
determine the required intensity of staining; the process of dehydra¬ 
tion always spoils the preparations more or less. 
With iron-hematoxylin I obtained the best results after wet fixation. 
The iron-alum and hematoxylin solutions of Grtibler were used. A 
saturated solution of lithium carbonate was added to the hematoxylin 
till a claret colour was produced (2—3 drops suffice). Preparations 
were left in the two solutions for 24—48 hours. The differentiation in 
iron-alum was controlled under the microscope; it took 1—3 minutes. 
Other stains, for instance hemalum (P. Mayer) and Ehrlich-Biondi’s 
stain (after Merkel’s liquid), gave rather indifferent results. Delafield’s 
and Carmin stains I found wholly useless. 
I will now discuss the influence of the different fixative and staining 
media on the structure of the nucleus, the blepharoplast, the flagellum 
(with the basal granule), the cytoplasma and the general cell form. 
1. Nucleus. In dried films, fixed with absolute alcohol and stained 
with Giemsa (^—1 hour) the nucleus is oval shaped. It is composed 
of a pink coloured matrix, in which a dark red substance is embedded. 
The first is structureless or has a more or less distinct alveolar structure 
(Fig. 2a — 2d). The dark red substance consists of a large central 
granule and two smaller ones situated in the periphery, having the 
