THK AXIAL GRADIENTS IN HYDROZOA. 19! 



rale of differential inhibition, acclimation or recovery, according 

 to the conditions of the experiment. The various forms, normal 

 and modified, are indicated in Table I. by abbreviations as 

 follows: 



/i. Norm.il bl.i-tula (Figs. I, 2). 

 IH. 1 )iti< i< in tally inhibited blastula (Figs. 4-9). 

 Af>. Spherical or tlattened apolar form (Figs. 10-1 ; 

 /./'. l.arly pl.mula (Fig. 3). 

 /./'. L.itr pi. null. i, elongated (Fig. 14). 

 //'. Differentially inhibited planula, shorter, thicker than 



norni.il, with excess of entoderm. 



//. Hydranth-stera axis developing directlv froi:i |..i-,il end of 

 planula attached by apical end; " normal " hydroid 

 ile\-li.pnn-nt (Fig. 15). 

 A7/. I l\dranth--tein axis developing directly from apolar form 



(Figs. 22, 23). 

 .V//. 1 1\ ilr.mth-stem axis developing indirectly by tran-tdrma- 



tion of , or budding from a stolon axis Figs 19 ji 

 >''. s i- Inn axis (Figs. ie iN, 24-29). 

 Dd. Dead. 



1 cl ' ' fable I. consisted of one hundred or more eggs or 



e.nl\ embiAos. All ditTerent forms observed \\eiv it.nrdfd at 

 each (Aaininaiion and many drawings were made. In the table 

 the relat i\ c ti<-i|ncncy of the different form-> i- rii'Jil\ indie. 

 I '\ cm 1 >~ini; iii | )arcn theses the designation- < ! tin -< t< n in- \s hich 

 \\i it- |>n i nt only in relatively small number^ (approximately 

 per cent, or 1< The designations not soencl"-ed repre-ent the 



eh.iracteri-tic forms of the series at the time indicated. As 

 indicated rious points in the table the >ohiti"ii- \\eie 



M'lnetinie- diluted after inhibition had occured. part icularK' 

 \\hen the appearance of the material indicated that di-\elo|>ment 

 \\a- not likely to proceed farther in the com cut rat ion originally 

 !. Such dilution made acclimation poible or hastened it. 

 The -erie- -i\eii are characteristic. Frequent re|)etitions during 

 the >ame and different summers showed nothing essentially 

 different from the data presented. 



I '. \ Series 4 1. as an example, the Table shows that in KCN, 

 'he tCrni- after one day \\en- inhibited bl.i-uil.e and 



