Egg Parasites and their Relatives. 1 51 



the clublike end of the threads. The contents, however, of 

 the joint when differentiated are not at once discharged as 

 perfect infusorioid spores, but are collected in a globular 

 head (Fig. 10) at the point of issue, where, after a time, each 

 individual acquires a membrane, through which (Fig. 11) the 

 spore at length bursts and moves about by the means of two 

 appendages (Fig. 12). 



The portion below the effete joint does not, as in the former 

 case, push forward into the cavity, but bursts laterally through 

 the walls, and as this process is repeated we have a forked 

 thread. 



The Oogonia are formed, as in Saprolegnia ferax, without any 

 lateral branches, and, as in that plant, its walls are perforated 

 with numerous holes. The antheridia in this species are, we 

 believe, unknown, but in a closely allied species, A. dioica, they 

 are produced, as in Saprolegnia dioica, on distinct threads 

 (Fig. 13) thrown up from the base of the tuft after the 

 sporangia have been formed. The threads are articulated in 

 the same way, and, commencing with the upper joint, the 

 contents are transformed into a number of globose antheridia, 

 each of which gives rise to a quantity of uniciliate bodies (Fig. 

 1 4), which escape from the common aperture, leaving the mother 

 cells behind. The process is repeated till it extends to four 

 of five joints. The minute bodies do not germinate, and, 

 therefore, as in the case of S. dioica, there seems little doubt 

 about their functions. 



We next come to Pythium, one species of which, P. mono- 

 sjpermum (Figs. 14*, 16), grows on dead insects in water. 



In this species the sporangia, which are produced on short 

 lateral branches, are solitary and extremely long (Fig. 14*), 

 with one, or sometimes two, shorter delicate appendages at their 

 base. The contents ooze out and form a globular mass (Fig. 15) 

 at the apex, in the centre of which the infusorioid spores are 

 formed. The Oogonia are small and globose, and with or with- 

 out a terminal thread or papilla ; lateral threads are given off 

 in their neighbourhood, the tips of which swell into antheridia 

 and penetrate the Oogonium through one of its apertures by 

 means of little rootlike processes, as in Saprolegnia monoica 

 (Fig. 7), thus giving rise to a solitary resting spore (Fig. 16). 



We have still to notice the fourth genus, which has been pro- 

 posed by DeBary under the name ofAphanomi/ces (Figs. 1 7 — 20), 

 a name which seems to imply a closo affinity with Fungi, if 

 not an immediate relation. Three of the species described 

 grow upon insects in water. This genus is distinguished from the 

 last by the peculiar mode in which the infusorioid bodies are 

 formed. Each is produced separately from tho contents of the 

 thread, and as one escapes another comes forward from behind 



