CENTRAL NERVOUS SYSTEM IN PLANARIA. 57 



Moreover, in Planar ia the auricles, like the eyes, show various 

 degrees of approximation and fusion and in the present paper 

 it has been shown th.it similar conditions appear in the cephalic 

 ganglia them-el\e-. In Planaria these monstrous forms can be 

 produced, not inrn-Iy by anesthetics, but by a variety of con.li- 

 tioii- tin essential efie.-t of which is a decrease in the rate of the 

 reaction-- in tln-li\iii^ -ystem. It seems probable that Stockard's 

 < \.-lope. m embryo- .uid the other intermediate forms between 

 .ui<l tin- normal animals are the result of a deriva-e in the 

 <>t reaction r.iilii-r than of any specific anesthetic effecl ot 

 either m.mne-inm -.ilt-, or alcohol. Moreover, thr double or 

 p.irti.illv double he. id- which Stockard obtained in some ca 

 are also p-.idiK .i> -counted for on a quantitative b.i-i-: a !>- 

 ised i. nr ot reaction means decreased correlation and thi- 

 ... n< lit ion f.ivor-, ph\ -iological isolation of parts and repr.'.Iuciion, 

 ;i- ihi- -enior autlior of tin- present paper has shown i-Ucwlu -n- 



Child, 'n 



1 IK- problem ol ilu- relation between morphogenesis and the 

 rate "t reaction in organisms is one of great important-, but it 

 h.i^ received i-omp.irati\-ely little attention. Current hypoth. 

 ol .li-\i-lo|uueiit .in.l inheritance scarcely consider the |)o-,i!,ilit\ 

 ot altering tin- rhuructeristic morphological features of t!i organ- 

 ism bv i-liaiue> in the rate of reaction, but of the fact there < an 



bi- no doubt. 



\'I. StMMAKV. 



1. Tin- ti i.ito|)hthalmic and teratomorphic forms of Planaria 

 tlnrot<>iff)liala can be produced experimentally by d.. ic.i-inu 

 the r.ite of the dynamic processes in the isolated pieces below 

 .1 certain \ari.ible le\el which is necessary for the product!.. n 

 o| not in.il I- 'i in-. 



2. In the-e forms the cephalic region of the IHTVOII- system 

 .litter- more or le^s widely from that of normal .mim.iU. The 

 tu.i -.nulioiiic masses are always less completely M-p.ir.ited 

 than in the normal animals and often only a -in^le - m-lion 

 de\elop>. In the teratomorphic form- the ganglia are more 

 .ibnormal thai; in the teratophalmic form-. 



V In the normal animals the cephalic ganglia extend a con- 

 -i.lei.tble (li-i.iiu-e anterior to the eyes and the l\\o -eparate 



