48 INTRODUCTION. 
displacement, for the entire anterior end of the spermatozoid of Volvox 
is certainly not blepharoplast. (The very suggestive theory of Stras- 
burger carries with it a certain degree of probability, yet to what extent 
it is true further research must determine.) 
If, however, any genetic relationship exists between centrosome and 
blepharoplast, the evidence is certainly to be sought in the lower 
plants. In this connection it is of the greatest importance to know 
first of all whether, in such alge as the Sphacelartacee, in which 
centrosomes are known, any relation exists between the centrosome 
and cilia-bearer, assuming, of course, that the cilia arise here also from 
a differentiated body. In Chara and in those Archegoniates' with 
blepharoplasts no centrosomes are found, neither is any such body 
known to take part in the formation of the spindle in such alge as 
Gidogonium, and others in which highly developed cilia-bearers 
occur. Although these facts do not prove anything, yet they lend 
encouragement to the belief that centrosome and blepharoplast may be 
homologous structures, or in some degree phylogenetically related. 
Those who maintain that the cilia-bearers are centrosomes have not, 
it seems, approached the question from the standpoint just mentioned, 
but seem to have based their conclusion upon the resemblance between 
blepharoplast primordia and centrospheres, or upon analogies between 
the spermatozoids in plants and the spermatozoa of certain animals. 
Belajeff (’99), who claims that blepharoplasts are homologous with 
centrosomes, strengthens his view by his observations in spermagenous 
cells of Marsiléa. In the grandmother-cells of the spermatozoids of 
this plant he finds that the blepharoplast primordia, which lie some 
distance from the nucleus, divide previous to the division of the nucleus, 
and between the two separating daughter primordia a small central 
spindle is developed just as in certain animal cells. From this small 
amphiaster the karyokinetic figure is developed. This, if true, is the 
first case on record in plants in which a central spindle is formed 
between the daughter centrosomes, lying in the cytoplasm some dis- 
tance removed from the nucleus. 
In the light of what is now known concerning the development of 
the spindle in Chara and in the Prerzdophyta, the author entertains 
serious doubts concerning the accuracy of Belajeff’s statement. Oster- 
hout’s (’97) studies on the development of the spindle in the spore 
mother-cells of Hgucsetum prove beyond all question that centrosomes 
are not present in that genus. In other Pteridophyta the majority of 
all investigations, which have been thorough or reasonably exhaustive, 
shows that centrosomes or centrospheres are absent there also, 
1 Marchantia polymorpha excepted. 
