Introduction to the study of fungi : their organography, classification, and distribution for the use of collectors . n byoospores is virtually the same,and this is almost the onlylink which unites them. It isworthy of remembrance herethat there is manifest in thisgroup a gradual loss of sex-uality, although external feat-ures remain much the same. The Saprohgniaceac, fromtheir aquatic habit, w^ould atfirst seem to have an affinitywith Algae, rather than withFungi, but this is ratheranalogy than affinity. Theliyphae, in most cases, aremodified at their extremity,and become zoosporangia,which a
Introduction to the study of fungi : their organography, classification, and distribution for the use of collectors . n byoospores is virtually the same,and this is almost the onlylink which unites them. It isworthy of remembrance herethat there is manifest in thisgroup a gradual loss of sex-uality, although external feat-ures remain much the same. The Saprohgniaceac, fromtheir aquatic habit, w^ould atfirst seem to have an affinitywith Algae, rather than withFungi, but this is ratheranalogy than affinity. Theliyphae, in most cases, aremodified at their extremity,and become zoosporangia,which are elongated cellsseparated from the rest of thehypha by a septum (Fig. 108).After the zoogonidia haveescaped through an opening atthe apex, the hj^^ha, or stem,continues to grow up throughthe empty sporangium, and forms a second sporangium, and this, in like manner, when thezoogonidia are discharged, may enclose a third, so that uponold threads it is not unusual to see the remains of two or threeempty sporangia, the one within the other. The zoogonidiaare produced in great numbers, in each zoosporangium, having. Fig. lOS.—Siiorangia and zoospores ofSaprolegnia. 234 INTRODUCTION TO THE STUDY OF FUNGI the common ovate form, with a pair of active cilia at thesmaller end. At maturity they escape by an orifice at theapex, and swim freely and actively in the surrounding addition to this asexual reproduction, there is a more com-plex system of sexual reproduction, by means of antheridia andoogonia, the resultant oospores, or resting spores, serving tocarry the germs through the winter and provide for theirappearance in the spring. In typical species the sexual appa-ratus is of this kind, the oogonia are globose cells, generallyterminal on short branches of the mycelium (Fig. 109). Theexternal membrane is absorbed at various points, lea\dng itpierced with rounded holes. The pro-toplasm becomes divided into a greateror less number of distinct portions,which become rounded in
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