THE GROWTH AND DIFFERENTIATION OF THE 
CHAIN OF CYCLOSALPA AFFINIS 
CHAMISSO 
WM. E. RITTER anp MYRTLE E. JOHNSON 
From the Laboratory of the Marine Biological Association of San Diego 
TWENTY-FIVE FIGURES 
FOUR PLATES 
CONTENTS 
PACE POSG-OinbNG ROSCADC Mh. Ge raratens lenses oveiays «'4,<,4 0,5 os NA PRE Rate 2 396 
LEYS jofetor tet REPS 1 Aiwa ES Segre Pots cise es a cn eDara Set UB Sahl UMM E C0 396 
Das Gemens leis eet ihe rete tee ets SEIN EGG cops S, She tsk A RO Roan ee 396 
Brief description of the species.............. veda avand ip beads «cok PR 398 
Measurements of the zooids of the wheels and of a portion of the chain not yet 
GNAVSLOLIRCG: INGO WIEOIS= feta tears 2 x Sod Sew he 5 geio ae ale. Seer eRe ea ee 399 
Dreatmientor Che cquswea ceed shay 225. o.oo. sare. Sa ~ ale eee 406 
Attempt to connect the formation of wheels with morphological, physiological, 
and mechanical phenomena presented by the animals................... 414 
1. Segmentation of the stolon, and the deploying point.................... 414 
2.. Position and relation of the zooids in the chain from the deploying point 
GO) DOSHL WAS elo pete. S5 oie uns iss | ns on ee ee 414 
ee OMIP GIN EYO ts the yZOOlUS yin 155) 0 sits 4 ca ee 414 
b Peduncles and foot-pieces.....:..........:...- gk te en 417 
c Emergence of the chain to the outside world........:........2.0.0% 417 
d “Dwastan the’ chain. 22. oh cs. oe oe ss 2. ee 418 
e Reduction of the foot-pieces, first break in the chain, and formation 
Olvthe imag WHEE. Figo. occ o's, 5 « 0,<.e eas, Soap hana ee ee 418 
3. Comparison of the rate of growth of the chain as a whole with the rate of 
other animals..... se A en IP RAMS Bets a Se oh eh a Sie 419 
Discussion of the observations from the causal standpoint.................... 420 
fC RAING GA RNG E RVs tics pes eyo e eK one's toi s size la eh ees See etc + 420 
2. Unequal growth of zooids and foot-pieces as a factor in the breaking up of 
HN CID RITIP PMS ered wea, oo eae ade' ew Siaee 6 o's ocd Re Re ee, SS 422 
3. Impossibility that the character of the blood supply to the zooids can be 
the cause of the size scheme within the wheels....................... 427 
4, Unlikelihood that the wheel arrangement of the zooids in Cyclosalpa has, 
as believed by Brooks, anything to do with the position of the first four 
plastozooidstofbyrosomlan =. 0 so ee eee: 429 
JOURNAL OF MORPHOLOGY, VOL. 22, NO. 2 
