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Part III — Seventh Annual Report 



and of late, more particularly, the able report of Professor Huxley"* a 

 considerable advance in the knowledge of Saprolegnia has been made. 

 We thus learn that Saprolegnia? may be considered as aquatic saprophytes, 

 which obtain their nourishment at the expense of decaying animal or 

 vegetable matter. 



In the Report of the Inspectors of Fisheries (England), Professor Huxley 

 details the result of producing Pringsheim's experiment, i.e., of placing dead 

 flies into water wherein Saprolegnia was growing. The spores on reaching 

 the fly germinate, sending inward through the cuticle the young hyphse 

 which permeate it in every direction, corresponding in this way to roots ; 

 while from the free surface shoots are sent out, so that latterly the insect is 

 surrounded by a delicate white aureole of hyphse. Fructification proceeded 

 with the formation of zoosporangia and subsequent liberation of the zoo- 

 spores ; whose life-history may best be detailed in his own words : — ' Each 

 zoospore, as it leaves the zoosporangium, is usually in active motion, being 

 propelled by the rapid lashing of two vibratile cilia, which are attached 

 to one point of its surface. After a few minutes it becomes quiescent 

 and surrounds itself with an extremely delicate transparent coat. But 

 this repose is of very short duration, as it soon emerges from its 

 envelope and moves about even more actively than before. It has now 

 an elongated oval shape, and has two cilia which proceed from one side 

 of the oval. This second state may last for a day, or perhaps two ; and 

 it is obvious that, from the activity of the motion of the zoospores to 

 say nothing of accidental currents, they may thus be carried a long way 

 from the parent stock. Sooner or later, however, they again come to a 

 state of rest, which is final, and they then usually germinate. That is to 

 say, one, or perhaps two, delicate filaments grow out and represent the 

 primitive hyphse of a new Saprolegnia.' 



Somewhere about the fourth or fifth day dictyosporangia were formed. 

 These are ordinary sporangia in which, however, liberation of the spores, 

 from some reason, is inhibited, and as a result of this they germinate, 

 penetrating the enclosing capsule with their young hyphse. So far the 

 method of reproduction detailed is of an asexual type, but under certain 

 not well understood conditions, a form of sexual reproduction, though of 

 a low type obtains. In these cases the terminal shoot is not converted 

 into a sporangium of the type already described, but assumes a form 

 more nearly approaching a sphere, and within this the contained proto- 

 plasm, by a process of division, is converted into a number of oospores, 

 this kind of sporangium being termed an oosporangium. Even this method 

 of reproduction may be asexual, the oospores being simply emitted, but 

 in other cases, a slender twig may arise by branching from the stalk 

 beneath the oosporangium or from a neighbouring stalk, and its terminal 

 portion slightly enlarging applies itself to the oosporangium. This having 

 been effected, a partition forms behind this terminal portion of the stalk 

 just as if it were about to be converted into a sporangium in the ordinary 

 way, when a condensation of its contained protoplasm occurs, and we 

 have what is known as an antheridium, corresponding to the male 

 element formed in higher plants. On the completion of this stage, a 

 portion of the antheridium penetrates the oogonium or female element, 

 and then breaks up into as many branches as there are oospores, to each 

 of which a branch is applied. Whatever be the conditions under which 

 oospores are formed, we know that they are true resting spores, and as such 

 capable of being exposed to various conditions whicji would be absolutely 

 detrimental to the young fungus or the ordinary zoospores. They are 



Reports of Inspectors of Fisheries (England), 1881-1886. 



