ASiectal Morphology and Classification. 325 
same or in different sporocarps (Figs. 447 1, 449 1). Fhe 
antheridia are either formed directly from the microspores, as 
in Marsilea and Pilularia ; or, in Salvima, the microspores 
[i 
FP ae 
SS eS 
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SES 
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= SS 
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SS, 
Fic. 447.—Salvinia natans ; 1. apiece of the plant Fic. 448.—Marsilea quadrt- 
with two aérial leaves, and one deeply divided folia, with two sporogonia 
root-like submerged leaf with sporogonia (natural (natural size). 
size) ; II. a section through two sporogonia ; @ : 
sporogonium with macrosporangia, 4 with microsporangia (greatly magnified). 
germinate and produce spore-sacs, the apices of which de- 
velope into antheridia. At the apex of the macrospore 1s a 
papilla of protoplasm from which is developed the primary 
cell of the prothallium or pro-embryo (Fig. 449 1. a). The 
