214 



BOTANY 



Gemmae. In Aneura multifida, two-celled gemmae have been de- 

 scribed, which escape from the cells of the thallus in a manner 

 resembling the escape of zoospores in the Green Algae. In other 

 genera e.g. Blasia multicellular gemmae, not unlike those in 

 Marchantia, are formed.. 



Tubers. In some Anacrogynae of dry regions, such as Geothallus 

 tuberosus, there is developed toward the end of the growing season a 

 subterranean tuber, which remains dormant during the dry season, 

 and starts into growth again with the advent of the winter rains. 



A. 



FIG. 173. A-C, Aneura pinnatifida. D,E, Pellia calycina. A, horizontal section 

 of young antheridial branch (X 565) ; x, apical cell ; , antheridia. B, transverse 

 section of archegonial shoot, passing through the apical cell, x ; ? , young arche- 

 gonia. C, nearly ripe archegonium (x 260). D, E, spermatozoids of Pellia 

 calycina (X 1225). (D, E, after GUIGNABD.) 



The Sporophyte. The first division in the embryo is always transverse. In 

 the Anelaterese this division at once separates the capsule from the foot ; but in 

 the typical Jungermanniales the lower of the two primary cells remains undivided, 

 or develops into a small appendage of the foot, and from the upper (" epibasal ") 

 cell are derived all the other parts of the sporophyte. This, in typical cases, 

 shows three parts : the capsule, seta, and foot. 



The sporogenous cells divide, as usual, into four parts, but the division is in- 

 dicated before the nucleus divides, in the form of four saclike outgrowths of the 

 cell, before any indication of division is shown by the nucleus. A " quadri-polar " 

 spindle is then developed, and the division- walls are formed between the four 

 young spores. 



