ZOOLOGY AND BOTANV, MICKOSCOPV, ETC. 395 



enclose the microspores until they develop their own cell-walls and the 

 wall of the mother-cell disorganizes, when the tapetal cells gradually 

 disappear. This long persistence of the tapetum is also true of Altheea 

 rosea. The spherical pollen-grain of Abutilon agrees with that of other 

 described Malvace^ in the number of nuclei and the structure and 

 composition of the walls. 



Seed-development in Parthenocarpic Fruits.* — G. Tischler has 

 studied the development of the seed-structures in parthenocarpic fruits 

 of Ficus carica^ Ananassa satim, Musa sapientum, and Muehlenheckia 

 platyclados, with the following results. In Ficus, endosperm-formation 

 takes place independently of any external cause, and although the cells 

 thus formed frequently abort, they often attain maturity and their 

 reserve-materials are identical with those resulting from fertilization. 

 The cells may enclose more than one nucleus each, but fusions then 

 take place. The unfertilized egg-cell often enlarges considerably, and 

 one case where cell-division occurred, is regarded by the author as an 

 instance of true parthenogenesis on a very low scale. In the ripe seeds 

 it appears as if there were several distinct groups of endosperm, and 

 in one instance the arrangement closely resembled that of an embryo- 

 sac with micropylar and antipodal regions, embedded in ripe endo- 

 sperm. 



In varieties of Ananassa obtained from Java, endosperm-formation 

 began independently of fertilization, but development usually ceased 

 before the appearance of cell-walls. In varieties obtained from Ceylon, 

 there was no parthenogenetic endosperm, but cellular outgrowths of the 

 nucellus were observed, which strongly resembled early embryonic 

 stages, besides which there were hair-like structures which swelled in a 

 thyllose manner. These phenomena were accompanied by a great 

 increase in the number of nuclei. In some varieties oi Musa, partheno- 

 genetic development continued as far as the formation of an eight-nuclear 

 embryo-sac, but degeneration then took place. In JIuehhnbecJcia there 

 is well-marked parthenocarpy, but everything aborts with the exception 

 of the stony outer shell of the fruit. 



CRYPTOGAMS. 



Pteridophyta. 

 (By A. Gepp, M.A. F.L.S.) 



Development of Marsiliacese.f — F. Schneider writes on the de- 

 velopment of the Marsiliacese, of which he has examined several species, 

 as well as Pilularia glohulifera L. Their anatomical structure differs 

 only in unimportant points. The axis, which has a strongly-curved 

 apex, grows by means of a three-sided apical cell, which is so arranged 

 that it turns one lateral surface to the ground. Thus there are one 

 ventral and two dorso-lateral series of segments. The division of the 

 segments was followed throughout, and the limits of the tissues traced 



* Jahrb. wiss. Bot., xxv. (1912) pp. 1-84 (2 pis. and 30 figs.), 

 t Flora, V. (1913) pp. 347-68 (figs.). 



