ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 603 



tozoids closely resemble those of many Gymnosperms ; they consist of 

 a long filament somewhat thickened in the middle and at its two ends, 

 and exhibiting at these spots a delicately porous structure. 



The author regards it as probable that a process similar in all essen- 

 tial poiuts takes place in all Angiosperms, with the exception of a few 

 abnormal case3, among which the Orchideaa may probably be ranged. 



Embryology of the Araceae.* — Prof. D. H. Campbell describes the 

 structure of the flower and the development of the seeds in species be- 

 longing to the following genera of Araceaa, — Dieffenbachia, Aglaonema, 

 Anthurium, Philodendron, and Lysichiton. The following is given as a 

 summary of results. 



In Dieffenbachia and Aglaonema there is no question as to the axial 

 origin of the ovule ; this is probably the case also in Lysichiton, but not 

 so certainly in Anthurium. In all the species examined there is a large 

 development of the base of the ovule, and in Aglaonema and Lysichiton 

 of the integuments also. The endosperm forms very early a continuous 

 tissue, completely filling the embryo-sac. In Lysichiton the antipodal 

 cells become very large and iindergo secondary divisions, so that a large 

 group of cells results. In Aglaonema there is a similar group of cells. 

 In the older embryo-sacs of Anthurium the antipodal cells could not be 

 certainly distinguished. There are probably two types of segmentation 

 of the young embryo ; in the first two transverse divisions are formed 

 before any longitudinal walls appear ; in the second there is a quadrant 

 formation suggestive of the early divisions in the fern-embryo ; the 

 differentiation of the organs takes place at a late period, and it is not 

 possible to trace them back with certainty to the primary divisions of 

 the embryo. The cotyledon is very large, the stem and root are much 

 less conspicuous ; in Lysichiton the root seems to be of lateral origin, as 

 it is in Pistia. A suspensor is never developed. 



The author regards the early development of a solid endosperm and 

 the great development of the antipodal cells as evidences of the primi- 

 tive nature of the Araceas. 



Embryology of Triglochin.f — Mr. T. G. Hill has carefully investi- 

 gated the structure and development of Triglochin maritimum, the follow- 

 ing being the more important results obtained. 



The vascular bundles of the flowering stem are of the collateral type, 

 and, when young, have a structure remarkably similar to that of the 

 same organ in several plants belonging to the Kanunculacese. The ovule 

 is basilar in origin. The embryo-sac often contains an increased number 

 of antipodal cells, varying from 3 to 14. The polar nuclei do not 

 appear to fuse until after fertilisation has taken place. The embryology 

 follows a normal course strongly resembling that of other Monocoty- 

 ledons ; a basal cell is developed, and it appears that this does not 

 undergo division. The embryo does not bend over, as in Alisma ; the 

 stem-apex is developed laterally. An endosperm is formed, the nuclei 

 of which are not separated by cell-walls ; they are very distinct, lining 

 the inner wall of the embryo-sac. 



* Ann. of Bot., xiv. (1900) pp. 1-25 (3 pis.). Cf. this Journal, 1899, p. 410. 

 t Tom. cit., pp. 83-107 (2 pis.). 



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