Osyris, Loranthus and Viscum. 209 



In the following explanation of the plates I have to observe that no mea- 

 surements have been given, because I found considerable variety in the state 

 of the fruit, belonging, if size only were consulted, to one period. I have 

 endeavoured to represent the development throughout, so as to give an intel- 

 ligible idea of the phsenomena with which it is accompanied. The dotted 

 lines visible in several of the sketches exhibit what I conceive to be the situ- 

 ation of parts removed from direct vision, and supplied by actual dissection ; 

 so that these sketches approach partly to the nature of plans. As such I 

 submit them with great deference; for however easy a tolerably accurate 

 delineation of what is under the eye may be, the sources of error are much 

 increased when minute internal parts are filled up from the ideas of their 

 relative situation derived from dissection. 



Tab. XVII. 



Santalum album. 



Fig. 1. Apex of an embryonary sac, of its perfect form; showing the apex to be apparently 

 divided, with fissures between the divisions, which look (in this one instance) as 

 if they originated from the membrane of the sac itself. The grumous nature and 

 division of the contents of the upper part of the sac, and the grumo-molecular 

 nature of that below, are distinctly seen. 



Fig. 2. Apex of another sac, intended to show (at a, a, a) the limits of the originally simple 

 sac. 



Fig. 3. Placenta halved irregularly, from a fully-expanded flower. Generally there is no 

 difference in length between the posterior extensions at this period. 



Fig. 4. Apex of an embryonary sac. The tube, near its broken edge, looks as if incrusted 

 with patches of grumous matter ; these are the aggregations of the grumous gra- 

 nular matter, and form the prelude to the subsequent cellularity. 



Fig. 5. Bulb of a more developed sac. a. The septum, which is invariably formed both in 

 barren and fertilized sacs. b. Indications of another cell or septum of excessive 

 tenuity. 



Fig. 6. Apex of a sac, seen with an object-glass of ^ of an inch focal distance. One of the 

 clearest instances of continuity of vesicle and pollen tube. 



Fig. 7- Ovulum, a little after fecundation. The hemispherical part of the bulb is now 

 cellular ; nucleary aggregation is distinct at both ends of the tubular portion. 

 The vesicle in this instance was empty. The place of future separation seen 

 at a, a. 



