( 90 ) 
My experience has not been long enough to enable me to assure 
that the objects will not fade in the long run, I ean only say, that 
even my oldest preparations, which have been enclosed in canada- 
balsam for a couple of years, have not faded visibly. I have taken 
care however to dissolve in xylol the solid, neutral canada-balsam 
of GRÜBLER’'s myself because the commercial solution often contains 
turpentine. 
The staining method here described has been suecessful with the 
cartilaginous skeleton of representatives of all classes of vertebrate 
animals, as for instance with Amphioxus, with embryos of sharks 
and rays, of salmons and roaches, of frogs and lizards, of birds, of 
mice, rabbits and man. 
With regard to man, it is of importance that the coloring can 
still be suecessful with embryos in a far proceeded state of dissociation 
and which otherwise one would be inclined to throw away. 
Magnified slightly, the preparations are particularly suitable for 
demonstration. I here demonstrate the skeleton of a human embryo 
of about five weeks old and draw your attention to the rudiment of 
the shoulder-blade. It is still exclusively adjacent to the neck, on a 
level with the 5%, 6 and 7 cervical vertebrae, with the point 
still above the first rib. Eleven ribs show the blue color of the 
cartilage, the undermost, the twelfth, not yet. 
In this second embryo, which is somewhat older, the shoulder- 
blade has left the 5 cervical vertebra and lies on a level with 
the 6 and 7 cervical- and the 1st and 2d thoracic vertebrae; it 
reaches with its point as far as the third rib. Not only all the 
twelve ribs are visible on the twelve thoracic vertebrae, the rudiment 
of a rib on the last cervical vertebra is seen besides, which rudiment 
fuses with this vertebra later on, as is well-known. 
In this third embryo, which I received in perfect condition and 
which after fixation was 25 mm. long in its natural curve, it may 
be seen that the shoulder-blade has again gone down a little. At 
the neck it does not reach higher than the level of the last cervical 
vertebra and reaches with the point as far as the 4 rib. Further 
the rudiment of the pelvis may here be noticed, on the level of the 
fourth lumbar and the first sacrum-vertebrae and on the head the 
cartilage of the occiput, the ear case, the cartilage of Meerrr and the 
rudiment of the incus. 
Other preparations show the paired rudiment of the rabbit’s and 
the chicken’s sternum. 
Also for macroscopic museum-preparations this is a suitable method; 
I could show you, for instance, the cartilaginous skeleton of shark- 
