112 ] The Classification of Lower Organisms 



Family 1. Monoblepharidacea [Monoblepharidaceae] A. Fischer in Rabenhorst 

 Kryptog.-Fl. Deutschland 1, Abt. 4: 378 (1892). Gonapodiineae and Gonapodiaceae 

 Petersen in Bot. Tidsskr. 29: 357 (1909). Producing extensive coenocytic filaments, 

 non-septate but with false septa of cytoplasm, anchored by rhizoids, reproducing 

 asexually by zoospores produced in sporangia which are usually terminal on the 

 filaments, the gametes produced in smaller antheridia and larger oogonia which are 

 in the more familiar forms terminal and subterminal on the filaments, the branches 

 commonly proliferating below them, the eggs without flagella. 



The species, about a dozen, form three genera. In Monoblepharis, the zygote, 

 being the entire protoplast of the oogonium, moves out of the oogonium through a 

 terminal pore, becomes attached in the opening, and develops a thick wall. In 

 Monoblepharella the zygote, retaining the flagellum of the sperm, swims for a time 

 before becoming encysted. Gonapodya resembles Monoblepharella (Johns and Ben- 

 jamin, 1954). Myrioblepharis Thaxter is believed not to be an organism; it is de- 

 scribed as something which might be produced if sporangia of Monoblepharis were 

 parasitized by an infusorian. 



Family 2. Blastocladiacea [Blastocladiaceae] Petersen in Bot. Tidsskr. 29: 357 

 (1909). Coenocytic filaments, in some examples of a false appearance of septation, 

 of the body type of the Rhipidiacea, i. e., differentiated into a basal cell anchored 

 by rhizoids and distal branches bearing reproductive structures, sometimes so re- 

 duced that the basal cell bears, or is itself, the reproductive structure; the reproduc- 

 tive structures including thin-walled zoosporangia, thick-walled resting spores which 

 germinate by releasing zoospores, and gametangia; the gametes morphologically 

 uniform or larger and smaller, all bearing flagella. 



These organisms are not familiar, although they are readily isolated by baiting 

 pond water, or tap water to which soil has been added, with hemp seeds or pieces of 

 fruit. There are four genera, Allomyces, Blastocladia, Blastocladiella, and Sphaero- 

 cladia, with about twenty-five known species. Allomyces is of interest for varied life 

 cycles, and Blastocladia for a peculiar type of metabolism. 



The first known species of Allomyces, A. Arbuscula, was discovered by Butler 

 (1911) on dead flies in water in India. The individuals are of the appearance of 

 minuscule shrubs, the branches divided by pseudosepta punctured in the middle and 

 ending in series of varicolored reproductive structures. Ordinary sporangia are 

 colorless, resting spores are brown, mature antheridia are pink, and mature oogonia 

 dull gray. Kniep (1929), in discovering the second species, A. javanicus, found that 

 the individuals are of two types, one bearing sporangia and resting spores, the other 

 oogonia and antheridia. Thus this organism has a complete life cycle of morpholo- 

 gically homologous haploid and diploid individuals. Kniep supposed that meiosis 

 occurs in the resting spores, and Emerson and Wilson (1949) established the point. 

 The chromosome number (n) oi A. Arbuscula is 7; that of A. javanicus var. macro- 

 gynus and of A. cystogenes is 14. 



The life cycle of A. Arbuscula is the same as that of A. javanicus. In A. cystogenes, 

 the haploid stage consists merely of the zoospores from the resting spores; these 

 become encysted and germinate by releasing isogametes. Thus this species has a life 

 cycle essentially of the advanced type characteristic of animals. There are further 

 species of Allomyces in which a sexual cycle is believed not to occur. 



In Blastocladia the basal cell bears directly multiple reproductive structures. 

 Organisms of this genus are less easily cultured than Allomyces; they require several 

 vitamins of the B group (Cantino, 1948). They tolerate oxygen, but do not require it. 



