150 Egg Parasites and their Relatives. 



antheridia filled with granules, which seem to have the power 

 of impregnating the contents of the Oogonia (Fig. 7). Pro- 

 cesses from the antheridia enter the apertures (Fig. 6) in the 

 walls of the Oogonia, the contents of which are soon trans- 

 formed into numerous large globose resting spores. These 

 like the others have the power of propagating the plant, and, 

 like the resting spores of some other Algse, are able to exist 

 some months without vegetating, though occasionally they 

 germinate in situ. As regards the vegetation in general, it 

 proceeds with the utmost rapidity, so that constant attention is 

 necessary to follow out the several phases satisfactorily. 



In Sajprolegnia ferax the first stage is precisely the same, 

 but there are no lateral branches by the contents of the tips of 

 which the Oogonia can be impregnated (Fig. 5). This is 

 the case also in some other species, in which impregnation 

 takes place by means of antheridia produced within the Oogonia, 

 or bodies resembling the Oogonia in form, or by antheridia 

 produced on certain threads, which after a time become free, 

 and attach themselves to the Oogonia, as in some genera of 

 Algae, where they are called by the Germans Mannchen, a term 

 equivalent to Homunculi. The different species are, however, 

 not at present perfectly characterised, and Pringsheim, who 

 has paid so much attention to these productions, and to whom 

 we are indebted for the greater part of our information, does 

 not profess to have placed every particular beyond doubt. 



In Saprolegnia dioica, however, he has shown that, after the 

 power of forming sporangia has been exhausted, a new crop 

 of threads springs up from the matrix, destined to produce the 

 antheridia. The upper portions of these threads (Fig. 8) be- 

 comes septate, and commencing with the uppermost joint the 

 contents become organized and re-transformed into myriads' 

 of minute bodies (Fig. 9), each of which bears a single thread- 

 like appendage. Those bodies are ejected from a terminal 

 papilla, but in the succeeding joints the point of egress is 

 lateral. They do not germinate like the infusorioid spores, aud, 

 as there seems to be no other mode of impregnation, it is con- 

 jectured that they pass through the apertures of the Oogouia, 

 and thus vivify the resting spores. 



Sa/prolegma ferax is extremely common on flies in autumn, 

 and may at almost any time be procured for examination by 

 simply placing a few of the languid flies which are so common 

 towards the close of the year in water. 



Achlya proUfera (Figs. 10 — 12) will, however, sometimes 

 appear on the same matrix, and possibly on other animal sub- 

 atances also. 



The first stage of this plant is very like that of Saprolegnia, 

 at least up to the formation of the first septum at the base of 



