1 76 Fertilisation 



doubtless originated from conjugating swarm-spores. In 

 time they have gradually lost their chromatic bodies, and 

 probably also their vacuoles. For the disappearance of 

 the former Schmitz describes a number of intermediate 

 steps. May I be allowed to quote the following sentences 

 from his important treatment of this subject :^^ "Some- 

 times, especially where the difference of the two kinds of 

 sexual cells is not yet very considerable, the spermato- 

 zoids act exactly like the isogametes, and like these 

 retain the chromatophores unchanged (e. g., in Scyto- 

 siphon lomentariiim). As that difference becomes greater, 

 however, the chromatophores of the male cells show a 

 distinct tendency to disappear, and especially does their 

 coloring become less intense (Bryopsis)/' 



This comparative study bridges the chasm lying be- 

 tween conjugation and fertilization, which is no doubt 

 chiefly due to the fact that, in the latter, the organization 

 of the protoplasts is inherited morphologically from the 

 mother only, while in the former, in some cells, the in- 

 heritance is from the mother, in others from the father. 

 But, on the other hand, the above mentioned phylogenetic 

 consideration leads to the conviction that the outer layer 

 of the spermatozoids has the same significance and the 

 same origin as that of the swarm-spores, and is just as in- 

 dispensable. 



4. Fertilization in Phanerogams 



In the seed-bearing plants, also, the organization of 

 the protoplasts is directly inherited from the egg-cell 

 alone. From the pollen-tube only the nucleus penetrates 

 into the latter; other parts, even if they should be neces- 

 sary for the transportation of the nucleus and should ac- 



i^Loc. cit. p. 121. 



