The structure & development of the mosses and ferns (Archegoniatae) . de further investigations upon the same subject,and added much to Hofmeisters account, but were also unableto determine the earliest phases of germination. Belajeff^ hassince given a clear account of the germination of the micro-spores, but up to the present time the exact method of formationof the female prothallium has remained doubtful. Recently afurther contribution has been made to the subject by Heinsen,^which, however, adds but little to our previous knowledge. The 1 Hofmeister (i). ^ ]\iniardet (i). ^ pfgffer, W. (i)
The structure & development of the mosses and ferns (Archegoniatae) . de further investigations upon the same subject,and added much to Hofmeisters account, but were also unableto determine the earliest phases of germination. Belajeff^ hassince given a clear account of the germination of the micro-spores, but up to the present time the exact method of formationof the female prothallium has remained doubtful. Recently afurther contribution has been made to the subject by Heinsen,^which, however, adds but little to our previous knowledge. The 1 Hofmeister (i). ^ ]\iniardet (i). ^ pfgffer, W. (i). 4 Belajeff(i). ^ E. Heinsen (i). 486 MOSSES AND FERNS CHAP. account of the female prothallium given here is based upon thewriters observations upon wS. Kraussiana, made from microtomesections of spores treated with chromic acid and embedded inparaffin. The Microspores and Male Protkalliuni The microspores of all species of Selaginella are smalland of the tetrahedral type. According to Belajeff^ they mayshow either a distinct perinium, or the latter is not clearly. Fig. 253.—a, B, C, Three views of the young antheridium of Selaginella Kraussiana (A. Br.), X 450 ;D, an older stage of the same, X480; E, F, two views of an older antheridium of 6. stolonifera,X480; G, spermatozoids of 5. cuspidata (Sk.), X1170 ; x, vegetative cell ; s, centralcells (after Belajeff). separated from the exospore. The spores contain no chloro-phyll, but much oil as well as solid granular contents. Atthe time that the spores are shed each one has alreadydivided into two very unequal cells, a very small lenticular cell(Fig. 253, x) and a much larger one which, as in Isoetes,becomes the single antheridium. The first wall in the antheridium divides it into two equalcells, each of which then divides into two others, a basal and 1 Belajeff (I). XIV 487 an apical cell. The latter divides twice more, forming threesegments, so that the young antheridium at this stageconsists of eigh
Size: 1449px × 1724px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookidstructuredev, bookyear1895
