476 MOSSES AND FERNS chap. 



carefully followed in E. fehuafcia. After the complete num- 

 ber of cells has been formed in the archesporium, and before 

 the tapetal cells are broken down, the sporogenous cells are di- 

 vided into groups which begin to separate from each other. 

 With the enlargement of the sporangium and the breaking down 

 of the inner tapetal cells these masses l^ecome isolated, and are 

 very easily removed from the sporangium (Fig. 240, A). 

 They usually consist of four cells, which in water swell up some- 

 what. In a fresh condition they appear quite colourless, but 

 the cytoplasm is densely granular. The nucleus is very large 

 and appears quite transparent with one or two distinct nucleoli. 

 In microtome sections of about the same age the numerous rod- 

 shaped chromosomes were very evident, but their number could 

 not be determined. The nucleolus is conspicuous, and on one 

 side, in a slight depression in the nuclear membrane were seen, 

 in some cases what were taken to be two centrospheres. The 

 latter were not always very evident, and the radiations which 

 are usually present about centrospheres, were not seen. From 

 the later investigations of Osterhout (i) upon E. liiiwsuin, it 

 is probable that the interpretation of these bodies as centro- 

 spheres was not warranted, as he failed to find centrospheres in 

 that species, and their presence in many other cases, where it 

 was supposed they existed, has been disproved. 



Osterhout has also shown that the bipolar spindle, observed 

 in E. fahiiafeia is a secondary condition. In E. limosum, he 

 found that about the time the spirem-filament had completely 

 separated into the individual chromosomes, a change was ob- 

 servable in the cytoplasm surrounding the nucleus. Up to this 

 time the cytoplasm in material treated with the Flemming triple 

 stain shows the characteristic orange or brownish coloration. 

 The cytoplasni immediately around the nucleus now stains a vio- 

 let color, and is supposed to assume the character of kinoplasm. 

 This kinoplasmic zone increases in size, and gradually assumes 

 more and more the appearance of a dense net of delicate fibres — 

 the future spindle-fibres. These begin to extend outward into 

 the orange cytoplasm and converge at numerous points, so as 

 to form a number of conical bundles radiating from the nucleus. 

 There is thus developed a multi-polar spindle, and as the nuclear 

 membrane gradually disappears, the free ends of these spindle 

 fibres penetrate into the nuclear cavity and come in contact with 

 the chromosomes, which gradually arrange themselves into the 



