AND GERMINATION OF ALGiE. 69 



rostrum, and the escape of a portion of it, are merely the 

 mechanism by which the opening is produced in the sporan- 

 gium destined for the admission of the spermatozoids. Im- 

 mediately after the formation of the opening in the sporangium^ 

 and in remarkable coincidence with the escape of the " cuta- 

 neous layer" through the rostrum, the " hornlet" opens at the 

 apex and pours out its contents (fig. 5). Innumerable, exces- 

 sively minute, rod-like corpuscles, most of them already nearly 

 isolated, thougli many at the moment of the opening of the 

 *' hornlet " still imbedded in the mucus, escape at once 

 though the orifice. Those already isolated exhibit an 

 extraordinarily rapid movement in all directions, and those 

 imbedded in the mucus do not become detached till after- 

 wards, when they follow the others with equal rapidity. The 

 field of view is soon covered with mobile corpuscles. In great 

 number (20, 30, or more) they enter the neighbouring orifice 

 of the sporangium, which they fill almost entirely (fig. 9), 

 penetrating through the portion of the cutaneous layer re- 

 maining in the sporangium, which, though obviously without 

 any definite membranous boundary, owing to its viscous, 

 mucous consistence, offers a solid resistance to their further 

 penetration into the sporangium. The corpuscles continue 

 thus to struggle forwards into the "cutaneous layer" for 

 more than half an hour ; bounding against its outer surface 

 they retreat, again push forwards, again retreat, and so on 

 in an uninterrupted succession of assaults and retreats — 

 wonderful spectacle for the observer! After this commotion 

 has lasted some time an abrupt boundary-line suddenly ap- 

 pears in the outer aspect of the " cutaneous layer " (fig. 10), 

 the first indication of a tunic forming around the contents of 

 the sporangium, which were before bare. From this moment 

 the mobile corpuscles are separated from the " cutaneous 

 layer" by a membrane which effectually prevents their further 



action upon the contents. They continue, it is true, to move, _^ 



to and fro, and in the roseate process, and this motion often \ l/Y 

 lasts for hours together, but at last they perish in the rostrum \ 

 itself, their motion becoming gradually slower and slower and 

 finally ceasing. Even after the lapse of several hours, and 

 when the act of impregnation has long been performed, the 

 quiescent, dead corpuscles may be seen in the rostrum, lying 

 on the front of the spore in the interior of the sporangium, 

 until at last they are completely dissolved and all vestige of 

 them disappears. The portion of the " cutaneous layer," re- 

 maining in front of the green contents of the sp)orangiu7n, 

 constitutes a thick stratum of a colourless and transparent 

 substance immediately within the orifice in the sporangium, 



