152 Egg Parasites and their Relatives. 



(Fig. 1 7) . When all have emerged each gradually acquires a 

 separate membrane (Fig. 18), from which it ultimately escapes, 

 moving about with one or two cilia (Fig. 19). The Oogonia 

 are globose. Impregnation takes place by means of antheridia 

 produced at the tips of lateral branches, as in Pythium. In 

 Aphanomyces steUatus the Oogonia are covered with projecting 

 papilla3 (Fig. 20). In A. scaber they are much less rough, 

 while in A. kevis they are quite destitute of warts. A single 

 resting spore only is formed in each sac. 



It remains only to notice a curious circumstance that, in an 

 unnamed species of Saprolegnia, Pringsheim has occasionally 

 found a single echinulate body formed within the Oogonium, 

 reminding one at once of the similar bodies observed by 

 Caspary and others, which are formed as a second kind of 

 fruit in Pcronospora. Cienkowski has also observed some- 

 thing very similar. This appears to be an additional argu- 

 ment for the reference of these curious bodies to Fungi. 

 Attention also may be called to the close resemblance of the 

 process of impregnation in Saprolegnia dioica to that which 

 Hofmeister is said to have observed in Truffles (Pringsh. Jahr. 

 Band 2), and still more to De Bary's observations on Oystopus 

 and Pcronospora, in the 20th volume of the fourth series of 

 Annates des Sciences Naturclles, just published, and of which 

 I shall hope shortly to give a report in the Intellectual 

 Observer. 



If I am asked to propose a remedy for the disease, I am 

 unable to make any plausible suggestion, as the substances 

 which might prove an impediment to the production of these 

 plants tnay prove equally detrimental to the eggs or fish which 

 it is wished to protect. I can only suggest that a weak solu- 

 tion of hyposulphite of soda should be tried in the case of a 

 few eggs, and, if it succeeds on a small scale, the experiment 

 might be easily extended. No one would be rash enough to 

 risk any great loss on a first experiment. 



The following are bhe principal treatises which have been 

 examined in llic preparation of this paper: — Gruithuisen in 

 Act. Leop. L821, p. 450, fc. 88. Cams in Ad, Leop. 1823, 

 t. 58. Pringsheim, Nor. Act. 1850, t. 46—50. Thnret 

 Etecherches stir les Zoospores des Algues, 1851. Do Bary 

 Beitrag zur Kenntniss derAchlya proliferaBotanische Zeitung, 



j. Cienkowski Algologiscne Stndien Bot. Zeit. 1855. 

 Pringsheim in Pringsheim Jahrb. Band I, Hell 2. Pringsheim 

 Band 2, Eeft 2. De Bary in Pringsh. Jahrb. Band 2, Heft 2. 



D] lOBIPTIONfl OF i'ii;i'i;KS. 



. 1 — 6. Saprolegnia /erase. — I. Groap of threads with 

 sporangia in different stages of growth, magnified. 2. Forma- 



