758 AQUATIC PHYCOMYCETES 



a discharge tube, endobiotic part a globose, obconical or pyriform 

 apophysis 4—5 [x in diameter from the tip of which a rhizoidal system 

 branches; zoospores ovoid or ellipsoid, 3-6 \x in diameter, with three to 

 six refractive globules and an elongate anterior flagellum, completely 

 formed within the sporangium and swimming away individually; rest- 

 ing spore not observed. 



Parasitic on oogonia of Aplanes sp., Japan. 



LATROSTIUM Zopf 

 Beitr. Physiol. Morph. niederer Organismen, 4: 62. 1894 

 (Fig. 55 A-D, p. 752) 



Thallus resting on and in the contracted ooplasm within the oogonium 

 of the host, monocentric, eucarpic, consisting of the rudiment of the 

 sporangium, which is sessile on the ooplasm, and a complex of extremely 

 delicate much-branched rhizoids arising laterally at one place on the 

 sporangial rudiment and penetrating the ooplasm; sporangium inoper- 

 culate, forming a broad discharge papilla; zoospores anteriorly uniflagel- 

 late, with a single globule, escaping fully formed through a broad apical 

 pore which does not penetrate the host wall; resting spore borne like 

 the sporangium, with a thick smooth radially striated exospore and a 

 thin smooth endospore, contents with an extremely large globule, ger- 

 mination not observed. 



Parasitic in oogonia of Vaucheria. 



The genus is founded on a species so like the debatable Rhizophydium 

 decipiens in habitat, shape of the sporangium, method of discharge, 

 and structure of the resting spore, that it seems hardly probable that 

 two organisms can be so alike in all characters except for the flagellation 

 of the zoospore and not be identical. Since the observations on zoospore 

 flagellation come from so high an authority as Zopf, however, we are 

 forced to assume their correctness, at least until further investigations 

 disprove them. If development is of the Entophlyctis type the genus 

 should be segregated in its own family. 



Latrostium comprimens Zopf 

 Beitr. Physiol. Morph. niederer Organismen, 4: 62, pi. 3, figs. 6-19. 1894 

 Sporangia from one to six in a host cell, broadly lenticular, with a 

 delicate smooth colorless wall which collapses after discharge of the 



