Vol. XXI. June, /p//. No. i. 



BIOLOGICAL BULLETIN 



SOME REMARKS ON I Hi: GASTRULATION OF 



DESMOGN Mill - n SCA. 



\VII.I.I.\M A. HII. l< i\. 



For tin- I.IM three <ir four years I have been trying to 



lll.lleri.il In eomjilete < il i-eP \ .1 1 \> HI- Ill.U le - Ulle I i I11C agO Oil tile 



,M~l filiation ol />, ! ri are many difficulties in 



the \\.iy n| dlit. lining tin- ri^ht stages f< >r this Mudy. for the 

 .in- u it In Hi l |ii^nieiit .1 in 1 eiirl. i-e<l in \ ,-ry tmi-h nieiiilnM' 



Ailile'l 1" tile ililtli lilt!' lei'tinll .lllil i 'Hell M t h HI . i- tile I.U't 



that the eggs are large .mil in.t e.i-il\ se< timie.1. 



As nieiiii'iiied in .in e.irlier p.iper, 1 \\i< <i thi> Bp ire 



lliilnlil.i-tir .ihli'Ul'Ji ;i|i|)fn.n -hilli: the lllenilil.l-tii- t\]>e 't 



FIG. z, i 'pi'iT lull ol .1 h.- .i..ti-'i --IN 



\\ith -in. ill y.-lk xr-niiil''- 



nieiit.ition. A moderate-sized M.i-tul.i r.ixity i- funneil. al'i.\e 

 it. MIL ill cells \\ith MIL ill yilk ur.mule- .ui<l ln-lnu, large <vll- 

 \\ith larger granule-. Tlii- r.i\it\ in l.ittT stages f< .iiu^ to In.- 

 more or le>- tilled in \\ith larger or Miialler i ell- \\liich round off 

 from the p-neral ma Figs. I and 2). To \\hat extent the 



1 \\'. A. Hilt. .11. ' t.i-n.i.il l-Y.itiii>> .'i an l-'arly 1 )r\ i-l. ipnu-nt nf Dcsmognathiis 

 i." J:>nr. Morpli.. \'ul. XX.. 1909. 



