94 BOTANICAL GAZETTE [august 



of his theory that the blepharoplast and the centrosome are 

 homologous structures. 



In Adiantum and Aspidium (Thom 84) the blepharoplast is 

 described as a round body in the cytoplasm of the spermatid. It 

 is stated that it does not act as a centrosome during division, though 

 no figures of these stages are shown. 



The most recent work dealing with the blepharoplast in pteri- 

 dophytes is that of Yamanouchi (97) on Nephrodium. In this 

 form there are no centrosomes in the whole life history. The two 

 blepharoplasts, which arise de novo in the cytoplasm of the spermatid 

 mother cell, take no active part in nuclear division, merely lying 

 near the poles of the spindle. In the spermatid the blepharoplast 

 elongates in close union with the nucleus to form the cilia-bearing 

 band. 



The first known blepharoplast in plants above the algae was 

 discovered in Ginkgo by Hirase (45) in 1894. He observed two, 

 one on either side of the body cell nucleus, and because of their 

 great similarity to certain structures in animal cells believed them 

 to be attraction spheres. It was not until two years later that this 

 investigator announced the discovery of the swimming sperm of 

 Ginkgo. In 1897 Webber (89) observed the same structures, 

 noting their cytoplasmic origin. On account of several differences 

 existing between these bodies and known centrosomes he expressed 

 the belief that they are not true centrosomes, but distinct organs 

 of spermatic cells, and first applied to them the name blepharo- 

 plast. Fujn (30, 31, 32) gave several figures of spermatogenesis 

 in Ginkgo, which agree with the accounts of Hirase and 

 Webber. The same subject has been dealt with more recently 

 by Miyake (67). 



In two short papers appearing in 1897, Webber described the 

 blepharoplast of Zamia (87, 88), and in 1901 a very full account 

 was published (90). According to this author two blepharoplasts 

 arise de novo in the cytoplasm. They are surrounded by radiations 

 up to the time of the division of the body cell, but these have no 

 part in the formation of the spindle, which is entirely intranuclear. 

 During mitosis the blepharoplasts, lying opposite the poles, become 

 vacuolate and break up to many granules which unite to form the 



