102 



THE SIMPLE HOLOCARPIC BIFLAOELLATE PHYCOMYCETES 



SAPROLEGNIINEEN-PERONOSPORINEENSERIES 



ZOOSPORES BlClUATE, DlPLANETK OOSPORES TYFKALLY DEVELOPED IN OOGONIA CELLULOSE TYPICAL. 



SAPROLEGNIINEAE 



CENTRAL SAP WCUOLE ZOOSPORES FORMED 

 BY AGGREGATION AT 7>€ PERPHZRY GERM- 

 IWWN IN TUBE OR SPORAN&JA SELDOM 

 CON/QIA LACK'VJ y 



PYTHUM-PERONOSPORINEAE 



FIRST S*ARM STAGE I ACXM fcuPPRESSEC) PYTHUM-TYPE AMD 

 DIRECT DEVELOPMENT OF SECONDARY SmRMERS PREDOMINATING 

 TUBE GERMNATIQN ABUNDANT CONIDiA FERTILIZATION OO- 

 GONIUM WITH ONE EGG PERPLASM 



SAPROLEGNIACEAE 



FIRST SWARM STAGE PRESET 

 OR REDUCED ACHWA-TYPE 

 PREDOMINATING PARTHENO- 

 GENESIS ABUNDANT OOGON- 

 IUM USUALLY WITH SEVERAL 

 EGGS NO PERPLASM 



LEPTOMITACEAE 



THALLUS CONSTRICTED 

 EIRS T SWARM STAGE OF- 

 TEN COMPLE TEL Y SUP • 

 PRESSED AND THE SEC- 

 ONDARY StWPMERS AL- 

 READY FORMED IN THE 

 SPORANGrVM FERTIL- 

 IZATION TYPICAL OO- 

 GOMUM WITH ONE EGG 

 PERIPLASM. 



APHANOMYCOPSIS 



ZOOSPORES DiPLANETlC ACH.YA-TYPE SEV- 

 ERAL ASEXUALLY FORMED RESTING SPORES OF THE 

 SAPROLEGN'ACEaE ■ T YPE IN A RUDIMENTARY OO - 

 GONIUM. I 



ECTROGELLA - 



CENTRAL SAP CAVITY ZOOSPORES FORMED BY AG- 

 OREOATCN ATT>£ PERpfCPY SEVERAL EATT CAN - 

 ALS ZOOSPORES OPLANETlC(ENCYSTNli WITH TWO I 

 QUA RESTNS SPORES SLIGJAUT FQRMCD NC L1Q&GRHORAE 



AMYLOPHAGUS 



SAP VACUOLES DISTRIBUTED FOOD VACUOLES PASSING 

 OVER INTO Tf€ ZOOSPORE RUDIMENTS ZOOSPORES 



WITH T*0 UNEQUAL CHJA. ONE RESTING SPORE PER 

 CYST 



, PROTOMONAS A*vfrLl 



\ FORMING A PLASMODIA* 



PSEUDOSPOROPS/S 



ZOOPORES WITH Z UNEQUAL OLIA 



PYTHIOGETON 



NO OOSPHERE NO PERPLASM 



I 

 ANCYUST/NEAE 



PYTHIUM-TYPE PREDOMINANT FERTILIZAT- 

 ION TYPICAL NO PREFORMED OOSPHERE 

 NO PERIPLASM 



OLPtDIOPSlS OEDOCONiORUM 



PYTHIUM-AND ACHLYA-TYPE OOSPORE NOT 

 FILUNG OOGOnVM NO PERIPLASM 

 I 



OLPfOOPSG 



h SC&NKIANA AS THE TYpty 

 ■ CENTRAL SAP VACUOLE ZOOSPORES BIOUATE, 

 DiPLANETlC WITHOUT ENCYSTHG, DIRECTLY trans- 

 formed AN OOSPORE SEXUALLY FORMED 



MONOBLEPHARIDINEAE 



boOSPOPES UNICILIATE NO CELLULOSE OOSPOPE 

 \DEVELOPEO IN AN OOGONIUM SPEPMATOZOCS 



MONOBLEPHAROACCAE 

 MONOBLEPHARIS GOHAPODrA 



CHYTRDINEEN-SERIES 



UNICIL1ATE, ZOOSPORE MONOPLANETIC CELLULOSE 

 LACKING OR EXCEPTIONAL AfC7>€N minimal 



ChfYTRID/ACEAE 



NO CENTRAL SAP VACUOLE ZOOSPORES POSTE- 

 RIORLY UNIOUATE MOTION GLIDING AND DARTING 

 RESTING SPORES BORNE FREE, SEYUALLY OR ASEY- 

 UALLr DEVELOPED. GERMINATING TO FORM ZOO- 

 SPORES 



BLAST OCLAUNAE 



ZOOSPORES POSTERIORLY UNIOUATE 

 SHGLE RESTING cell formed free IN 

 .. AN ^CONSPICUOUS OOGONIUM GERMI- 

 NATING TO FORM ZOOSPORES NO 

 CELLULOSE 



BLASTUUDUvf 



CENTRAL SAP MCUOLE OUT OL 'UM 



SPHAER/TA, CLPlDlUM 



POOOPROCTA (ECT08ELLA) PLATEAU// 



NO RECEPTION OF FORMED FOODS [i) EYTRANEOUS FOOD RESIDUE PRESENT' 

 ZOOSPORES with TWO EQUAL CHJA 



PSEUDOSPORA LEPTODERMA 



CENTRAL SaPCaviTY ZOEtSPORES FORMED BY AG- 



GREGATION AT Tf€ PER/PMJ- y TMO SHWPhASES 



BARBETA PSEUDOSPORA f UWSTWTit HARTOG 



ZOOSPORES WfTH TWO EQUAL QUA C tNTRAL SAP CAVITY ZOOS- 



- PORES FORMED BYAXR EGAT/OH AT Tf£ PERlPlCPY 



ECTOBELLA BAMBEKII 



/ NO EYTRUSON OF FORMED MJTFfliONAL RES- 

 CUE ZOOSPORES UWOLMTE RESTING 

 SPORES OF P€ QVTROiACEEN-TrPE 



PSELCOSPORA tvfYZOCYTODES ^ 



ZOOSPORES IN CYSTS RESTING SPORES^- * <* 



PSEUDOSPORA (PS PARASiTCA AS TYPE) 



WORON1NA GLOMERATA^ 



_APHELILaOPS!S_ 

 zoospores bicil1ate 



GYMNOCOCCUS CLADOPHORAE 



_ AMOEBOAP HEL!DIUM_ 



ZOOSPORES WITH vUT CILIA 



APHELIDIUM -GROUP 



ZOOSPORES POSTEPOPLT UHCA.IATE 



AMOEBOID NAKED PROTOPLAST M/TPITION ANTMAL-LIXE ZOOSPORES AND RESTING SPORES NOT EOPUTD IN CrSTS 



Diagram 1. Showing the origin of the Pliycomycetes from the zoosporic Monadineae or Proteomyxa. After Scherffel, '25. 



stitute the basis and starting point of what Scherffel 

 n('25) earlier named the Saprolegniales-Perono- 

 sporales series of Oomycetes, as is shown in dia- 

 gram 1. In his opinion, this series has four outstand- 

 ing characters which distinguish it from the Chytri- 

 diales on one hand and the Monoblepharidiales- 

 Blastocladiales series on the other. These characters 

 are : ( 1 ) biflagellate diplanetic zoospores which lack 

 a large conspicuous refringent globule; (2) grayish 

 granular appearing protoplasm and the presence in 

 the zoosporangium and oogonium of a large central 

 sap cavity or vacuole surrounded by a relatively 

 thin parietal laver of protoplasm, and the occurrence 

 of simultaneous centrifugal cleavage (ballung) ; 

 (3) lack of motile male cells or spermatozoids and 

 the production of sexual or asexual oospores in 

 oogonia, and ( t) the presence of cellulose in the 

 cell walls. Scherffel believed that these characters in- 

 dicate close affinity within the series and that these 

 fungi constitute an ascending evolutionary line ori- 

 ginating in the zoosporic Monadineae and culminat- 

 ing in the Peronosporales. Although Scherffel pre- 

 sented more specific and pertinent data in support of 

 this view, his theory is fundamentally the same as 

 that proposed by Dangeard in 188(i and 190(5. 



Mez, on the other hand, concluded from his serum 

 diagnosis method of determining affinities that the 



origin and relationships of the holobiflagellomycetes 

 are otherwise. He believed that the Saprolegniales 

 originated from the Siphonales near Vaucheria and 

 by reduction gave rise to the Lagenidiaceae, from 

 which in turn was derived the Woroninaceae (in the 

 broad sense of Minden) by further reduction. How- 

 ever, his belief concerning the two last named fami- 

 lies was not based on experimental data, because of 

 the difficulty of obtaining sufficient material for 

 serum analysis. Mez's view is accordingly scarcely 

 more than a revival of the reduction hypothesis of 

 DeBary, Tavel, and other workers. More recently 

 Bessey has suggested that the Olpidiopsidaceae (in- 

 terpreted as including all of the biflagellate species 

 except the Lagenidiaceae) as well as the Chytridi- 

 ales have evolved from unicellular heterocont algae 

 through the loss of chlorophyll and the assumption 

 of a parasitic mode of life. As is shown in diagram 

 2, his theory of origin and relationships of the Pliy- 

 comycetes is based primarily on whether the second 

 flagellum is retained or lost in evolution — the Olpi- 

 diopsidaceae and Lagenidiaceae being derived from 

 those ancestors which have retained both flagella. 



If we examine closely the data on phylogeny in 

 these four families we find, however, that they are 

 very incomplete and not so convincing as the above- 

 mentioned workers would have us believe. Beginning 

 with the Rctrogellaceae, for instance, it is obvious 



