ACIILVA 95 



The follmvins seven cultures were all made on hard boiled egg yolk 

 in (listiliecl water with the chemical added as indicated: 



III O.I per cent KXOj. Strong srowtli. No sporangia. A few good gemmae. No sexual 

 reproduction. 



In O.I per cent KIUPOi. C.rowtli good. .\ very lew sporangia willi normal discliarge. 

 No gemmae or sexual reproduction. 



In O.I per cent XajHPOi. Strong growth. Aiiundant sporangia proliferating repeatedly 

 and discharging normally. A very few gemmae. No sexual reproduction. 



In O.I per cent KiSO,. Strong growth. Sporangia plentiful. Gemmae abundant. No 

 sexual reproduction. One sporangia was seen discharging. The emergence was 

 rather slow, and the last few spores were very slow and showed obvious swimming 

 movements in the sporangium on escaping. About a dozen clung to the tip of the 

 sporang'um. The others spread in a 1 ose flock, showing slow movements, and every 

 now and then one would swim briskly away. 



In O.I per cent Cas(POi).. Strong growth. Many sporangia, quite norma'. A very few 

 gemmae. No sexual reproduction. Several sporangia seen to dis harge. In two 

 cases six spores detached themseKes and moved away, in another case four. 



ACHLYA Nees v. Esenbeck, 1823, p. 514. 



Resembling Saprolegnia essentially in size, growth and appearance 

 of vegetative parts and as now constituted approaching that genus closely 

 in some species. Sporangia typically (except in the Racemosa group) 

 broadest in the middle or towards the base, gradually pointed, not in- 

 creased from within others but by lateral branching from below the older 

 ones, at times in close clusters, again in more interrupted sj'mpodial 

 arrangement. Spores on leaving the sporangium coming to rest at 

 once, or after a short period of slow rocking, in a hollow sphere or irregu- 

 lar cluster (in several species at least furnished with cilia during emer- 

 gence), encysting there and after a few hours swimming again as in 

 Saprolegnia. Oogonia borne \'ariously as in Saprolegnia, with or with- 

 out pits or papillae. Eggs formed of all the contents of the oogonia 

 and not completeh' filling them, one to many; varying in structure with 

 the different groups. Antheridia of near or distant origin, androgynous 

 or diclinous, in a few species absent; fertilizing tubes usually present. 

 Fertilization has been demonstrated in A. americana var. cambrica and A. 

 polyandra Hildb. by Trow, and in A. deBaryana by Trow and by iMucke 

 (see these species for details). We ha\-e observed the passage of living 

 material from the antheridium into the egg of A. Orion, and it is very 

 probable that fertilization occurs in a number of other species. 



The species of Achlya can be divided very naturally into several 

 distinct groups or sub-genera which are separated by the internal struc- 



