262 THE MICROSCOPICAL NEWS. 
This apparatus need only be seen at work for its simplicity and 
excellence to be duly appreciated; and those who, like myself, 
have succeeded, after much trouble, in hatching fish ova under a 
domestic water-tap, will thank Mr. McDonald for his useful 
invention. 
DOUBLE STAINING NUCLEATED BLOOD 
CORPUSCEES: 
R. VINCENT HARRIS has been experimenting upon this 
subject ; a great many colours have been used in combination, 
and from his experiments he draws the following conclusions. The 
details of the various trials may be found in the last April number 
of the Quarterly Journal of Microscopical Science :— 
1. The only entirely successful combinations were the following : 
Rosein and anilin green. 
Fuchsin and methylen blue. 
Fuchsin and Bismarck brown. 
Eosin and vesuvin. 
Iodine green and Bismarck brown. 
Hoffman’s violet and Bismarck brown. 
Anilin violet and methylen blue. 
2. The green dyes were not at all permanent. I have proved 
this with both malachite and iodine greens. 
3. Even with the above successful combinations the results 
varied in a most extraordinary manner, whilst the circumstances of 
the staining operation and the solutions appeared to be unvaried, 
the very greatest care being required to produce a constant result. 
One thing necessary for success was certainly that the solutions 
should be quite fresh. ' This is likely to prove a great objection to 
the general introduction of anilin dyes into use. The simple 
method of dehydration employed, of course, could not be employed 
in the preparation of tissues, although it does for blood, sputa, &c. 
4. The result was materially affected by the time each dye was 
allowed to remain in contact with the blood. 
It is worthy of note that according to the evidence of competent 
authorities, various chemically diffused anilin dyes have been sold 
under the same commercial name ; and so, both in the preceding 
notes and also in the annexed table, it should be said that the 
anilin dyes used were obtained from Messrs. Hopkins and Williams, 
Hatton Garden, W.C. The following table (drawn up August, 
1882) includes the dyes used in above experiments : 
