THE FORMATION OF THE, SPERDEATOPHORE. EN 
ARENICOLA AND A THEORY OF THE ALTER- 
NATION OF GENERATIONS IN ANIMALS 
ELLIOT ROWLAND DOWNING © 
FOUR PLATES AND SEVEN TEXT FIGURES 
CONTENTS 
WoOcatlonco tether a: Oma See iy cos sees reo Ss we aoatbas soe Bl bla ceraicne one Ree 1002 
IMIGIG NOVO NSa ata: ers aici cae co tla dip ee lo accel aa DE Et saci PIE M 2A SS Sa 1002 
JbitoattHsyroy tiie] okeyeecoy ct2 V0 [See es EL eae Gane eee een oe ae ea Wes yd 1004 
General statement of spermatophore formation..........................-- 1006 
TB pRECC ines lO) ONIN these ech arent Se ORR grit ae ee se Aaa he casey coc 1007 
Degeneration and phagocytosis of the gonad................:..scseetes- oe 1008 
EixtrapOLoodsviesselseiOrsaeralOmene 4: cle. sc-2c'ssioces Aree aet eee oe neon 1009 
Origin of the spermatogonia from peritoneal cells.......................... 1011 
SPLUCTUMeTOMALNesPOM AG dem mpds Mega ce aise: clara et Uae ciete, Aa eet eee ea 1012 
Mhesspermatophores;, their formations, .% 6.56.5... wale gale bs nee re 1013 
‘Pheirdischargeimto the body: Huds ..2 0. kek ceo oe ce Soe ee eee 1014 
ARhem-analory, to blastulacandagastrulae.. <..... 1.2445 ot oo eeeen eee 1015 
RH eirsbehavaGrawlenerio ere ter eee arcs ol kcws bats ak ce eee See 1016 
CUP An isp CLEAALOPORIB. <p newin sme fess Sco b Sys Rds a Pe Ga see pega 1017 
Spermatoconial macromenres and micromercs: ..0..-.644.5 eee eee 1018 
The spermatophore originates from one primary spermatogonium by a process 
om cleavare-andein yarimAbiOns a40m- ears. osteo So 3.5. oe Rie SRE: oO 1021 
The spermatophore an individual—the gametozoon.....................+.. 1022 
iEhe-alfernahion: Of penerstlonp retin cc ooo)... Sox cscs nes ae eee eas octet 1023 
Botanic se OF the terme ny ot 6 ciel oe ne Se RO es Pe 1023 
Wsialezoolocicaltsioniticancenseerenen erie. eee eee ae eee 1023 
Alternatiom and chromatininedUetiam errs) ti oss. sk aaa deen. oo aoe eee 1023 
Independentpsphenomenawe ww reer ani cake ee koi ee ee eae 1024 
Chamberlain’s theory of the alternation of generations in animals........... 1028 
Objectrommiovel Geert eeee Lee es ere Or cea gob ice v.06 ss oa ee 1029 
Limits of the gameto- and sporo-generations.....o.') 20.0%. .25. 2+. . sineles Bae Bee 1029 
iinstratedt by eTraphiesliieshistonrlcsmareas tener. 6 2. oes aa 1030 
DexUalIty And Tem WCION ep sve eee Petts Be Mie WCB) iho, Sede ct date Se Se aae ee 1033 
AdiacentapnenOmlemst rey ere TARE hea ee eis seals cna nra.ct ae 1033 
iINotmecessarily;causalllyarelatedieeereen sn nee ese ca eee 1033 
The primitive animal type and the development of the alternation of genera- 
tions as found: ine Arentcolacn cece on sere eet ane be ce OS ee ae 1084 
