366 LIBBIE H. HYMAN. 



was ether. It was found that distal pieces are more susceptible 

 to ether than proximal pieces, that more of them die when both 

 kinds of pieces are exposed for a certain length of time to a given 

 concentration, and that of those that survive, the regeneration is 

 more delayed in the apical than in the-drotal halves. An experi- 

 ment of this kind is recorded in Table I. In this experiment the 



TABLE I. 



DIFFERENTIAL SUSCEPTIBILITY OF APICAL AND BASAL PIECES OF EQUAL LENGTH 

 (10-12 MM.) TO 2 PER CENT. ETHER. 



Exposed to ether for twenty hours. Table records condition of the pieces seven 

 days after cutting. Temp. 12 2 C. 



Condition. Apical. Basal. 



No. of hydranths emerged 5 14 



No. of pieces with primordia of hydranth 1 5 7 



No. of pieces living but without primordia 1 2 15 



No. of pieces dead 1 38 14 



hydranths and first millimeter or two of the stems were dis- 

 carded, the stems were then cut into two equal pieces, each 

 10-12 mm. long, and all of the distal pieces placed in one finger 

 bowl and the proximal in another. A solution of 2 per cent, 

 ether in sea-water was then poured on both sets of pieces as soon 

 as possible after they were prepared and they were left in this for 

 twenty hours. They were then thoroughly washed and left in 

 normal sea-water. The temperature throughout was 12 C. 2. 

 The condition of the fifty pairs of pieces seven days after cutting 

 is shown in the table. The greater susceptibility of the apical 

 pieces is perfectly evident. More of them have died than in the 

 case of the basal pieces and of those that survived, the basal 

 pieces are much in advance in the process of regeneration. 



C. GRADIENTS IN REDUCTION OF POTASSIUM PERMANGANATE. 

 Child (190) has called attention to a new method of demon- 

 strating the metabolic gradients. This method consists in 

 exposing the organisms to appropriate concentrations of a readily 

 reducible substance like potassium permanganate. This sub- 

 stance is reduced by protoplasm, a brown precipitate of manga- 



1 Pieces were examined with the compound microscope. Pieces showing smooth 

 munded ends and circulation were counted as living, while stems containing only 

 masses of granules were regarded as dead. 



