116 Morphologie, Teratologie, Befruchtung, Cytologie. 



embryosac is the product of union of several sporogenous cells. 

 The first nuclear divisions in the embryosac result in four free 

 nuclei arranged in pairs; in A. simplex and A. modestum one of 

 the upper nuclei gives rise to synergidae, the other becomes the 

 ovum-nucleus. The two chalazal nuclei remain individed until after 

 the egg-apparatus is complete; subsequently they divide, but there 

 is no nuclear fusion preliminary to the first formation of endosperm, 

 and no antipodal cells; A. pictum has perhaps antipodal cells. The 

 first formation of cell walls in the endosperm occurs when there are 

 four free nuclei; development proceeds from base to apex of embryo- 

 sac. The first endosperm cells are smaller and comparable to anti- 

 podal cells of other Avaceae. The synergidae remain intact and 

 appear to contribute to the tissues of the embryo, which is large. 

 The chalazal region of the ovule is enlarged and may function as 

 a perisperm. The plates include 41 figures showing details. 



* W. G. Smith. 



Chamberlain, C. J., Morphology of Ceratosamia. (Bot. Gaz. 

 LIII. p. 1-19. pl. 1. Jan. 1912.) 



The Mexican cycad Ceratosamia prefers a much more shaded 

 habitat than does Dioon, and in its development from the seedling 

 stage shows great ränge in size and divisions of its leaves. There 

 is also much Variation in the size and number of sporophylls in the 

 ovulate strobilus. As far as studied, development of the male game- 

 tophyte follows the same course as in other cycads, resulting in 

 the production of two or even four sperms. Besides the primary 

 haustorium, several secondary haustoria develop from the end region 

 of the pollen tube. The female gametophyte shows an exceptional 

 feature, in that the small ventral canal nucleus may enlarge and 

 fertilize the egg, although fertilization generally occurs in the 

 normal way. The suspensors may unite so that from five eggs may 

 develop from one to five embryos. M. A. Chrysler. 



Price, S. R., The Roots of some North African Desert- 

 Grasses. (New Phytologist X. p. 328—340. 1 plate. 2 figs. 1911.) 



The roots of grasses collected on the sand dunes of Ain Sefra 

 (Algeria) were examined with reference to the sheath called by 

 Volkens, "sand-stocking" or "caddis-worm {Phyrganeae) case". 

 Aristida pungens, Desf. is dealt. with in detail. This has long (20 

 metre) cord-like roots with a wiry stelar Strand, enclosed in a broad 

 cortex with outside it a sandy sheath in which root-hairs are inclu- 

 ded; the root-hairs are active throughout the whole length of the root. 



Before the roots could be microtomed, the sand-grains were 

 removed by hydrofiuorie acid without serious damage to the tissues, 

 except near the root-tip. Internally the relation of the meristematic 

 layers to the root-cap is of the liorhizic type (Van Tieghem). At 

 the root-tip the piliferous layer is noteworthy in that each cell is 

 elongated radially, and these cells are regarded as mucilage-secreting 

 by modification and swelling of the outer portion of the cell walls 

 which are renewed by the protoplasmic contents. These gland-cells 

 exist for about 6 mm. behind the meristematic apex. Where the 

 tissues of the root have attained maturity, there is a piliferous layer 

 over several layers of exodermis, which inwards pass over into an 

 inner cortex with intercellular Spaces. The other tissues are mono- 



