270 THE PHENOMENON Of 



mucilaginous layer. The somewhat distant elevations 

 become more and more rounded, and the mucilaginous 

 layer, drawing itself apart between them, becomes finally 

 wholly contracted into them. The hemispheres thus 

 formed are therefore not closely crowded, as in the 

 formation of the gonidia, but separated by largish inter- 

 spaces. The next process is the rounding and detachment 

 from the cell- wall, in consequence of which the spores lie 

 free and loose in the interior of the spore-case, and are 

 not scattered until this decays. The form of the spores is 

 always globular ; the size varies in Saprolegnia prolifera 

 from So to 55 millim., while the gonidia in the stage of 

 motion are only ^^5 milim. long ; the colour is brown j the 

 contents are at first finely granular, subsequently inter- 

 mingled with drops of oil; the membrane is at first 

 imperceptible, when fully developed thick and evidently 

 double. In the cylindrical spore-cases, the hemispherical 

 elevations are formed in pretty regular alternate order on 

 the two opposite sides of the cell-wall, so that they are 

 interposed like the teeth of two wheels or racks; but 

 the detached spores fall into a single linear row. In the 

 expanded cases the arrangement of the spores does not 

 exhibit any definite order. The number varies very 

 much according to the size of the cases. I have seen as 

 many as twenty spores in one case, while in many other 

 instances there were only four, three, two, and not very 

 unfrequently there was only one. 



The formation of the spores of Leptomitus ladeus 

 resembles that occurring as an exception in the cylindri- 

 cal cases of Baprolegnia; the spores detached from the 

 wall of the mother-tube are arranged in a single row.* 

 The formation of the spores in the sporangia of Coleo- 

 clicete takes place in a manner similar to that in the 



* Leptomitus ladeus is in every respect allied to Saprolegnia. The dieho- 

 tomous filaments are not articulated any more than those of Saprolegnia, 

 but only divided into sections by regular strictures ; these sections have 

 been taken for closed cells. It is only in the fructification that isolated, 

 mostly terminal sections are actually shut o£F, swell up to some extent, and 

 become spore-cases. No active gonidia seem to occur. 



