290 H. MAllSHALL WARD. 



the tube — at any rate^ not as protoplasm ; but that the tube 

 remains closed at the end, and never enters the substance of 

 the oosphere; on the contrary, the antheridium either 

 remains coiled round the oogonium, or the tube which it 

 sends into the cavity simply touches or pushes the oo- 

 spheres. Ho thus thought that the fertilising influence must 

 pass through the closed walls of the tube which remains 

 closed. 



Pringsheim, in 1874/ again examined the question, and 

 came to the conclusion that Cornu was wrong, and that where 

 the tube comes in contact with the oosphere it remains quite 

 distinct from it, however closely applied. Thus no slow pass- 

 age over of protoplasm into the substance of the oosphere 

 occurs, and hardly any, if any, contents of the antheridium 

 disappear. Pringsheim further came to the conclusion that in 

 some cases, since the oospheres become ripe oospores 

 without any antheridial branches coming near them, the phe- 

 nomenon must be considered one of parthenogenesis. 



De Bary's lately published views have been already referred 

 to. He finds, after prolonged and exact researches, that not 

 only does no observable passage of anything take place through 

 the fertilisation tubes; not only does the naked oosphere 

 clothe itself with a membrane (thus indicating that it no longer 

 requires fertilisation) without the contact of the tube, but that 

 normal, ripe oospores are produced habitually in some forms 

 without an antheridium branch ever being formed at all. 

 Such cases De Bary considers not '^parthenogenetic," in 

 Pringsheim's sense, but apogamous. 



One more point may be shortly adverted to. It appears 

 as said to be a constant phenomenon in certain forms, perhaps 

 in all, that the masses of protoplasm forming the oospheres 

 throw off smaller or larger portions of their substance during 

 their amoeboid movements preceding their final rounding off 

 as smooth oospheres; if these detached masses of protoplasm 

 are to be regarded as of the nature of the " polar cell " 



' ' Jabrb. f. wiss. Bot.,' B. ix. 



