26 THE OPHIOGLOSSALES 



cells, as m the case ol Botrychium lunar i a, are nearly square in outline, most of the 

 walls in tin cover cells being at right angles to each other, as in Botrychium. 



I he divisions in the central cell are verj similar to those in Ophioglossum and 

 Botrychium, anil the original quadrant divisions are perceptible for some time. 



1 he number ol spermatocytes, as in Ophioglossum and Botrychium, may be very large. 



I'he spermatozoids were not seen by Lang, but from a comparison of the nuclei of 

 the spermatocytes they are apparently of about the same size as those of Botrychium. 



SPERM VTOGENESIS. 



Ophioglossum is especially suited to a study of spermatogenesis, owing to the 

 very large size of the spermatozoids. Those of 0. pendulum are probably the 

 largest known among the Pteridophytes. In material fixed with i percent chromic 

 acid, or weak 1* lemming's solution, and stained with gentian violet and aniline 

 safranine, the coloring is beautifully clear and the blepharoplast stains with extra- 

 ordinary sharpness. The spermatozoids of O. pendulum are larger than those ot 

 0. moluccanum or 0. vulgatum, but the development is very much the same. 



It the sperm cells are examined previous to the final division to form the 

 spermatocytes (plate i, fig. in), the nucleus will be seen to have a small but distinct 

 nucleolus and a dense reticulum. The whole nucleus stains strongly with safranine. 

 I he cytoplasm is fairly dense, with granules of various kinds in it. In material 

 fixed with !• lemming's solution there are often small black specks, probably fattv 

 bodies, which sometimes interfere somewhat with the study ol the cytoplasm. In 

 well-stained sections the blepharoplasts may be seen as two small, rounded bodies 

 of a \ iolet color ( plate t, fig. 1 6, bt) lying near the nucleus. Several cases of the final 

 nuclear divisions were nut with, but all of these wen- in material fixed with chromic 

 acid, and the blepharoplasts wire not very well differentiated (plate 2, \\^. n). I he 

 nuclear spindle is ver) distinct, and the very numerous chromosomes are so crowded 

 rhat it was quite impossible to determine their number exactly, but it is very large. 

 In the young spermatocytes (plate >, fig. 26) the nucleus shows a more or less con- 

 spicuous reticulum, but the nucleolus has disappeared, as it usually does at this 

 stage in all the forms that have been studied. The further development of the 

 spermatozoid corresponds very closely with that of Equisetum (see Campbell 4 and 

 Belajcff I, 2). One of the blepharoplasts in the primary spermatocyte goes with 

 each daughter cell I the definitive spermatocyte) and can be seen as a distinct rounded 

 body lying near the nucleus (plate 2, fig. 24). In some cases what appeared to be 

 the blepharoplast was King in a depression at the periphery of the nucleus, and 

 looked very much like a nucleolus. 



Before the nucleus undergoes any marked change, the blepharoplast begins 

 to elongate (plate 2, figs. 26, 27) and assumes the form of a pointed, slender, strongly 

 staining body lying near the nucleus. This body is really somewhat ribbon-shaped, 

 and more pointed at one end than the other, and it is also somewhat curved, even 

 in its earlier stages. A transverse section appeals crescent-shaped. The nucleus 

 now elongates slightly and the reticulate structure becomes very conspicuous (plate 

 2, fig. 25). There are large, strongly stained granules, which are probably composed 

 of several more or less coherent chromosomes, as the number of these granules is 

 very much less than the number of chromosomes in the nuclear plate of the dividing 

 nucleus. The blepharoplast continues to elongate, and in favorable cases the young 

 cilia can be seen growing from it, but none of my preparations showed the cilia 

 nearly so plainly as Belaieff's figures show 7 them in Equisetum and Gymnogramme. 

 There is no doubt, however, that the cilia arise in much the same way as BelajefF 

 describes. The nucleus now becomes indented on one side and assumes a crescent 



