ACHLYA 141 



Trow found that in his plant the anthcridia were suppressed when 

 bits of mycelium with >oung oogonia were cut off and ])ut in a moist 

 chamber. 



It was on tliis \-ariety that Trow did a good piece of cytological 

 work and caiiic to the well-founded conclusion that fertilization takes 

 place. As to cytology and fertilization of the egg his conclusions may 

 be briefly summarized as follows: The ^■egetati^•e nucleus has a membrane 

 and a central spongy body containing chromatin and nucleolar matter 

 Irom which linin tlireads extend to the membrant'; the nuclei divide 

 in the hyphae and large numbers enter the sporangia and the oogonia; 

 in the former no divisions take place, but in the oogonia many at least 

 of the nuclei divide mytotically, with the number of chromosomes prob- 

 ably four [?]; after this division there are about ten times as many nuclei 

 as there will be eggs and all now degenerate except the number necessary 

 to supply each egg with a single nucleus, which becomes the egg nucleus. 

 The antheridia are multinucleate and their nuclei "undergo exactly the 

 same changes as those in the adjacent oogonia." In fertilization a tube 

 containing one male nucleus touches the naked egg and discharges into 

 it a nucleus and some protoplasm. The egg and sperm nuclei then to 

 all appearances fuse, though the process was not followed through all 

 stages. The ripe egg contains a single nucleus, and may germinate at 

 once or after as long a rest as four months; the nucleus divides mytot- 

 ically to produce about twenty nuclei, showing about eight chromo- 

 somes. The egg now sprouts to form sporangia or hyphae. 



Achlya deBaryana Humphrey. Proc. Am. Phil. Soc. 17: 117. 1892 



11893]- 

 Achlya polyaudra deBary. Beit. z. Morph. u. Phys. d. Pilze 4: 



49, pi. 4, figs. 5-12. 1881. 

 Not Achlya polyaudra Hildb. (See Humphrey, '92, p. 118.) 



This has not been recognized in America, and we take the following 

 from deBary's condensed statement of 1888 (p. 364): 



"Main hyphae stout, usually ending in ]>rimary sporangia under 

 which the secondary ones appear in sympodial arrangement. Oogonia 

 short-stalked, racemosely arranged, seldom intercalary and often ter- 

 minal on slender hyi)hae; wall stout, here and there with somewhat thin- 

 ner places but not i)itted, occasionally with a few wart-like projections. 

 •Antheridial branches almost always androgynous, much contorted and 

 branched, arising from the same principal a.xes which bear the oogonia, 

 but never from the oogonial stalks. Antheridia on the branched tips 

 of the antheridial branches attached by their sides to the oogonia and 

 sending into them one or two fertilizing tubes each. Eggs varying in 

 number, but mostly numerous, eccentric." 



