SAPROf.EC.NIA 4.^ 



Davis ('03) worked witli a jilant that would l)C'tt\'r haw Ik'^u called 

 5. fcrax than .S'. mixta, as it l)()re no anthrricha at the tinu- he was i)ut- 

 ting up liis preparations. His results were in general the same as Claus- 

 sen's for .^. ntonoiai and Trow's for 5. mixta and 5. diclina, aside from 

 fertilization plunomena (wliieh were of eoursc absent) and with the exeej)- 

 tion of eerlain detailsof tile strueture and division of the nucleus, in whicii 

 he corrected Trow in se\eral jioints. His attacks on Trow's conclusion 

 that fertilization did occur wiiere antheridia were present have pnned 

 since to be entireh' unjustified. r)a\'is found four chromosomes in the 

 division in the oogonium, a matter of much interest in this partheno- 

 gcnctic form, as Claussen found the number to be 10-14 in S. monoica 

 where fertilization occurs. The spindle is entirely intranuclear. The eggs 

 are freciuently binucleate and rarely trinucleate. 



The [lioneer work in the physiology of this group was done l)y KIel)s 

 who worked on a plant that normally on flies in water showed only 10- 

 20S0 of oogonia with antheridia. He considered the plant 5. mixta, 

 but according to our rule it would fall under S. ferax. For this reason 

 werefer here to his conclusions although we do not know that his plant 

 really was S. ferax. The important results of his work are summarized 

 by him as follows (translated) ('99, p. 582):* 



1. Uniiucmipted continuous growth: — in all good nutrient media, so long as fresh unaltered 



luitriciit is present, e. g., in water with peas, in weak meat extract (1-2*^), in gelatin 

 with peptone, in mixtures of water with albumen, casein, etc. 



2. Prompt and complete transformation of the mycelium into sporangia and /oospores: — - 



by placing a well-nourished mycelium in fresh water. 



3. Growth with continuous formation of zoospores: — in very weak solution of certain nutri- 



ents, e. g., 0.005^ haemoglobin, also in luycelium on agar-albumen jelly that is put in 

 running water. 



4. Acti\e formation of oogonia with limited growth: — by putting a well nourished myce- 



lium in agar-agar. 



5. Active growth, then acti\c formation of oogonia: — 



(a) oogonia with antheridia: — in solution of leucin (o.l'^o) with tricalcium phosphate 

 (0.1%). 



(b) oogonia without antheridia: — in solution of haemoglobin (0.05-0.1%). 



6. Growth, then formation of s[)orangia, then of oogonia: — by placing the mycelium in 



water from gelatin-meat extract; or by culture on dead insect in water. 



7. Growth and simultaneous formation of sporangia and oogonia: — in water witli some 



fibrin or syntonin. 



8. Growth, then formation of (xigonia and later sporangia: — after strong nutrition ol tin- 



mycelium transfer to 0.01% haemoglobin. 



9. Active formation of gemmae: — by putting a well nourished myceliiun in o.6',o trical- 



cium phosphate, or 1% sodium chloride, etc. 



*An even more condensed and somewhat modified restatement of his results is made 

 by Klebs in his Willkurrliche Entwickelungsiinderungen bei Pllan;:en, p. 41. Jena, 1903. 



