204 ERNEST WARREN. 



the capsule is fully formed, it has not been found possible to 

 cut satisfactory sections. The circumstance is, however, of 

 less importance as the capsules are exceedingly transparent. 

 It is probable that the difficulty in cutting- is due to the 

 impermeability of the capsule to the paraffin-wax. 



The capsule itself is refringent, but it stains readily with 

 Delafield's haematoxylin. 



I have treated some fragmentary sections with a series of 

 reagents in order to endeavour to test the nature of the 

 capsule. I have had no opportunity of testing fresh material ^ 

 in a similar manner. 



Cellulose tests. — It is coloured faintly yellow by liquor 

 iodi ; it is slightly disorganised by concentrated sulphuric 

 acid ; it is not coloured blue with iodine and sulphuric acid ; 

 it is not appreciably swollen or dissolved by an ammoniacal 

 solution of cupric hydrate. 



The capsule accordingly does not give a characteristic 

 cellulose reaction. 



Proteid tests. — Concentrated nitric acid causes a faint 

 yellow tinge both in the capsule (especially in the outermost 

 layer) and in the perisarc and mesoglea of the hydroid. On 

 the addition of 50 per cent, caustic potash or ammonia the 

 yellow tinge becomes somewhat intensified. There would 

 thus appear from this test, the xanthoproteic reaction, that there 

 is some proteid matter both in the capsule and in the perisarc. 



Neither 50 per cent, caustic potash nor concentrated 

 ammonia have any appreciable swelling action on the capsule. 



Concentrated hydrochloric acid and aqua regia do not 

 obviously affect the capsule. 



Picric acid has no marl;ed staining effect. 



Delafield's hasmatoxylin stains the capsule and the mesoglea 

 intensely, while the perisarc is somewhat less strongly acted 

 upon. 



Methyl blue stains the capsule deep blue. 



Methylene blue is an excellent stain for the capsule and 



1 The hydroid had been fixed with a half-satvirated solution of corrosive 

 sublimate in 30 per cent, spirit with li per cent, acetic acid. 



