412 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VI. 
sections are washed in water, dehydrated, cleared in oil of cloves and 
mounted in balsam. The preparations show that in the parts in which 
organic iron is present phosphorus occurs, and that a fainter reaction for 
phosphorus obtains in the spongioplasm. 
Held* found the Nissl granules are not digested in pepsin and hydro- 
chloric acid solutions. This is correct, but the oxyphile nuclear substance 
also digests and the nucleolus under certain circumstances disappears. 
This is an important fact and is the chief objection to calling the 
oxyphile nuclear substance oxychromatin, for chromatin is always con- 
sidered to be indigestible. Held’s figures seem to show that he obtained 
the same result on digestion. No mention is made of this in his text, 
but in the description of the cells given under his plate he adds, “ Nuc- 
leolus und ein Theil der Kernmasse noch nicht verdaut,” thus indicating 
that he considered it an ordinary circumstance for nuclear parts to 
digest. 
The oxyphile nuclear substance digests very readily indeed, but it is 
doubtful if the disappearance of the nucleolus is really due to the diges- 
tion of its substance. I shall show later that the nucleolus has an 
oxyphile centre and it is probable that this centre would digest, thus 
liberating the whole nucleolus, if it were attached to the slide only by 
its centre. If on the other hand, the nucleolus is attached by its 
- periphery it will not be removed. Sometimes the nucleolus, after diges- 
tion, appears as a shell. The nucleolus is also very loosely attached to 
the nuclear network, a feature to which v. Lenhossek®” has called 
attention and which will afterwards be discussed. After digestion the 
deepest iron-alum stain of Heidenhain or any other stain, will not show 
a reticulum in the nucleus, consequently there would be nothing to hold 
the nucleolus in its place in material digested in bulk. Considering 
everything, it is probable that the peripheral or basophile portion of the 
nucleolus is never digested. It is not the weak acid that affects 
the oxyphile nuclear substance, for one may leave loose sections 
in weak (0.2 per cent.) hydrochloric acid for days at 37° C.and yet the 
nucleus will contain oxyphile substance. 
In the digestion experiments fresh material was sometimes first 
submitted to digestion and then hardened and imbedded, but generally 
the tissue had been fixed in alcohol beforehand. The material 
employed was in the form of sections attached to the cover glass 
or in thin pieces which were afterwards dehydrated and then imbedded. 
31 Held, Arch. t. Anat. u. Phys., Anat. Abth., 1895, p. 396. 
32 v. Lenhossek, M., Arch. f. Psych., XXIX, p. 373. 
