Fecundation of the Ovum. 393 



name of filament serving as an anther, and which actually per- 

 forms the part of an anthcridium ; and, in the second place, of 

 the slightly recurved organ ])laced close beside it, to which 

 Pringshcini thinks we should give the name of sporangium rather 

 than that of spore. In the course of its development, the 

 sporangium, which is at first only a simple papilla, acquires a 

 kind of beak-like process, turned in the direction of the antheri- 

 dium. These two organs are then in direct communication 

 by their bases with the tube of the Vaucheria, and enclose the 

 same contents as the latter ; but they soon separate from it, 

 each forming a septum. The sporangium becomes transparent 

 on its free side, in consequence of the accumulation in that part 

 of the substance called the pellicular layer* {Hnutschicht) by 

 I'ringsheim, whilst the antheridium also becomes transparent, 

 but by the metamorphosis of its chlorophyll and the remainder 

 of its contents. The pellicular layer continuing its development 

 causes the sporangium to cleave at the place of the beak-like 

 process, and project externally. The part which has thus 

 issued separates in the form of a mucilaginous mass, and soon 

 decomposes. By a very remarkable coincidence, as soon as the 

 sporangium has split open, the point of the antheridium also 

 opens and pours out its contents. A mass of small moveable 

 corpuscles issues from it, which, lashing the water with their 

 tails, move in crowds about the sporangium, pressing against the 

 pellicular layer. x\s the beak of the sporangium and the parts 

 in its neighbourhood are completely transparent and destitute 

 of chlorophyll, it is easy to make perfectly sure of the penetration 

 of the corj)UScles [spermatuzoids) into the interior, if this takes 

 place. This is the case, according to the observations of Prings- 

 heim. One or more spermatozoids penetrate into the interior 

 of the pellicular layer, and the latter then, in common with the 

 rest of the contents of the sporangia, becomes surrounded by a 

 membrane which Mohl might this time consider as a true 

 primordial utricle, but for its want of primordiality. It is the 

 mucilaginous pellicular laj'er itself that becomes converted into 

 membrane ; for in proportion as the latter thickens, the former 

 disappears. This cell, which fills all the interior of the sporan- 

 gium, is therefore the true spore, the result of fecundation. In 



* This is, in fact, the primordial utricle of ]\Iohl, of which Pringsheitn 

 disputes the membranous nature. He has shown that the membranous 

 appearance is due to the reagents erai)loyed, which cause the substance 

 to contract. With sufficiently weak reagents, a mucilaginous mass is 

 obtained ; but nothing that can be compared to a membrane. See 

 Pringsheim, Grundlinien einer Theoric der Pflanzenzclle, Berlin, 1854 ; 

 in abstract in Mohl and Schlechtcndal's Bot. Zeitung. 25th May 18.55. and 

 Annals. 2nd Ser. xv. p. .'^47. 



