418 Dr. Hanstein on tfie Fecundation 



the four cells. The process is completed in from eighteen to 

 twenty-two hours. Soon afterwards the solid exosporium of the 

 androspore breaks up, and the contents enclosed by the delicate 

 inner membrane escape ; the contents either burst the membrane 

 during their escape, or form a transparent spherule from which 

 the daughter cells issue by degrees and set free the spermato- 

 zoids. 



These have previously been in whirling motion ; they burst 

 *their mother cells singly, and hurry from them with the rapidity 

 of an arrow. Each spermatozoid consists of a corkscrew-like 

 filament, to the last remarkably large turns of which a large 

 globular vesicle adheres ; the latter contains numerous starch- 

 granules in a clear fluid, and resembles an independent cell 

 surrounded by a sufficiently firm membrane. This is by no 

 means a part of the mother cell, which, on the contrary, remains 

 behind empty after the escape of the spermatozoid. The screw- 

 like filament has twelve or thirteen turns; it is very closely 

 twisted at the apex, and is beset, especially on the lower and 

 wider turns, with numerous very long cilia, which, when bent 

 forwards in swimming, often project beyond the tip of the screw. 



In the meantime the prothallium with the archegonium has 

 been developed on the macrospores. Even before the escape of 

 the macrospore, its vertex, inflated in the form of a wart, is filled 

 with yellowish finely granular plasma, while the rest of its space 

 contains the well-known large starch-grains, oil-drops, and pro- 

 teine substances. Several hours after the escape of the spore, 

 this lentiform mass of protoplasm is still undivided by any per- 

 ceptible septum from the rest of the inner space of the spore, 

 and is therefore not a complete cell ; but in about five or six 

 hours it is cut off" by a proper cellulose membrane. Soon after- 

 wards its plastic contents separate into a roundish central prin- 

 cipal mass and a peripheral layer which is thicker towards the 

 free upper surface ; the latter then gradually divides into smaller 

 and smaller portions, which surround the central mass in a 

 single layer. The cell-body thus sketched out, but not com- 

 pleted, breaks up at the slightest touch ; but subsequently first 

 the central and finally the peripheral parts surround themselves 

 with resistant cell-walls, which enter into close mutual con- 

 nexion. 



The central cell is then the primary cell of the nascent arche- 

 gonium, the mother cell of the germ ; the peripheral cells form 

 the prothallium. In the middle of the basal surface the central 

 cell is sometimes in immediate contact with the septum between 

 the prothallium and the interior space of the spore, and is there- 

 fore excentric. Exactly at its vertex four regularly placed cells 

 soon exceed the others in size, and rise into a wart, each of them 



