MARSILIA VESTITA. I93 



end seems to be quite free from them. When the sper- 

 matozoid escapes from its mother-cell there is attached, 

 as in other spermatozoids, a delicate vesicle (v) con- 

 taining more or less granular matter. Some of the 

 granules are starch, others seem to be albuminous. This 

 vesicle usually becomes detached when the spermatozoid 

 is held in the mucilaginous matter about the macrospore 

 where they accumulate in very large numbers, hundreds 

 often being visible about a single macrospore. Evidently 

 this mucilaginous matter exercises an attraction apart 

 from that thrown out by the ripe archegonium, as 

 they collect about the macrospore long before the 

 archegonium has opened. In studying them, they were 

 killed with a drop of weak osmic acid about }^ percent., 

 and then stained with a little gentian-violet. In this way 

 they may be killed instantly without anv distortion and 

 the cilia rendered very distinct. 



If we compare now the antheridium of Marsilia with 

 that of the other Filicinea^ we tind, as might be expected, 

 the nearest affinity with Pilularia, from which it differs 

 mainly in the less perfect development of the dome- 

 shaped wall in the antheridium mother-cell, and the more 

 distinct separation of the two groups of sperm-cells, 

 which, as we have seen, are hereremarkablv distinct. In 

 Pilularia these remain distinguishable up to the time that 

 the antheridium is ripe, bui this is less marked than in 

 Marsilia. In the Polypodiace^, which are the nearest 

 among the homosporous ferns to the Marsiliacea?. this 

 division is indicated in the early stages of the anther- 

 idium, but is finally lost. 



THE MACROSPORE AND FEMALE PROTH ALLIUM. 



The macrospore of Marsilia is the most specialized 

 found in the Pteridophytes. This is true both of the 

 peculiar wall, which however it shares with the nearlv 



