398 XXIX. THE GYN(ECIUM OF ANGIOSPERMS. 



project somewhat into the cavity of the cells, and bear two or 

 three rows of ovules. The middle line of each cell is represented 

 by a slight depression. At these points lie weak vascular bundles, 

 while a strong one externally and a weaker one internally lie at 

 the outer edge of the septa. The inner one, by means of horizon- 

 tal branches, which the cross-section often lays bare, is -connected 

 with the bundles which occupy the central tissue between the 

 four cavities. These for their part nourish the placentae. The 

 wall of the ovary contains numerous raphides which, set free from 

 their cells, lie scattered over the whole section. 



An adherent or " inferior " ovary is, from a philogenetic or 

 evolutionary point of view, to be considered as a hollowed floral 

 axis, filled up by and completely adherent to, the ovary of a syn- 

 carpous pistil. Its wall might be expected, therefore, to some- 

 times, at least, show signs- of its composite character, and possibly 

 the two bundles juxtaposed to the septa are such. The anatomical 

 and physiological data for this theoretical view are, however, often 

 wanting, though Eschscholtzia californica (the yellow Californian 

 poppy, an annual very common in gardens), many Kosaceae, Saxi- 

 fragaceae, etc., are of great interest in this connection. Often we 

 are bound to conclude, however, that the structure of the wall of 

 an " inferior " ovary, i.e., of an ovary wall plus receptacular tube, 

 does not recognisably differ from that of a free ovary, i.e., of an 

 ovary wall alone. 



Structure of the Ovule of Aconitum. We will now endeavour 

 to become acquainted with the structure of the ovule, and at the 

 same time learn something of the processes of fertilisation in 

 Angiosperms. To study the separate parts of the ovule, we first 

 prepare cross- sections through the ovary of the Monkshood, 

 Aconitum Najwllus, or of some other species of Aconitum. We 

 select a flower in full bloom, strip off the other parts of the flower, 

 and then cut through the three ovaries together. Care should 

 be taken that the sections are made correctly, at right angles with 

 the long axis of the individual ovaries. The number of sections 

 must be considerable in order with more certainty to cut an ovule 

 correctly. We glance over the sections, and select those which 

 appear likely. In case the section is not delicate enough, we can 

 help matters with a little potash. If an ovule is cut centrally, it 

 appears as in the adjoining Fig. 145. The ovary is monocarpel- 

 lary, in all essentials resembling that of Delphinium ; the ovule 

 arises from a marginal placenta. It is inserted thereon with a 



