THE CENTROSOME AND THE BLEPHAROPLAST 87 



nlso present in the cytoplasm. Similar in most points is the account 

 of Schaffner (1908). Miyakc (1905), as the result of his studies on 

 Marchantia, Fegatella, Pellia, Aneura, and Makinoa, believes that such 

 liverwort centrosomes are merely centers of cytoplasmic radiation, and 

 inclines toward the view of Strasburger that the blepharoplast and the 

 centrosome are not homologous structures. Escoyez (1907) finds two 

 ''corpuscles" appearing in contact with the plasma membrane in each 

 cell of the penultimate generation in the antheridia of Marchantia and 

 Fegatella; they occupy the spindle poles and function as blepharoplasts 

 in the spermatids (the cells which transform directly into spermatozoids) . 

 Bolleter (1905) believes the centrosome-like body in Fegatella to arise 

 within the nucleus. 



In the antheridium of Riccia Lewis (1906) reported centrosome-like 

 bodies in both the early and diagonal divisions. They apparently arise 

 de novo in the cytoplasm prior to each mitosis, showing no continuity 

 through succeeding cell generations except after the last mitosis, when 

 they persist and become the blepharoplasts. 



iaras 



FIG. 28. Spermatogenesis in Blasia. 

 b, blepharoplast; n, nucleus. X 4200. (After Sharp, 1920.) 



Woodburn (1911, 1913, 1915) has given accounts of spermatogenesis 

 in Porella, Asterella, Marchantia, Fegatella, Blasia, and Mnium. He 

 finds that the blepharoplast is first distinguishable as a special granule in 

 the cytoplasm of the spermatid, and holds that it represents, as Mottier 

 (1904) had formerly suggested, an individualized portion of the kinoplasm 

 arising de novo in certain spermatogenous cells. In a more recent con- 

 tribution (Sharp 1920) it has been shown that in Blasia (Fig. 28) a 

 blepharoplast is present at each spindle pole during all stages of the last 

 spermatogenous mitosis, and that in the spermatid it fragments as it 



