Dr. Dickie on the Ovule of Euphrasia officinalis. 261 



and of high authority in points relating to vegetable physiology 

 had made such statements, and implicit confidence was placed 

 in them. Tubes were observed, but for the reasons alluded to I 

 felt convinced that they had origin from the ovule itself. 



Additional observations have led me to change the opinion 

 formerly expressed respecting the part of the ovule from which 

 these organs in Euphi-asia are derived, and the present commu- 

 nication has reference to that point, and to a peculiarity in the 

 structure of the ovule of that plant, which, so far as I am aware, 

 has not been hitherto described. 



The substance of the nucleus is very thin about the period of 

 fecundation, the embryo-sac which lines it becoming highly de- 

 veloped. This sac is attenuated at the posterior extremity ; its 

 body tapers gradually upwards into a neck, which is bent at an 

 obtuse angle, and near the apex it is bulbous ; at this apex or 

 anterior extremity there is the appearance of a fissure or cleft 

 bounded by two or three rounded lobes. Tn the interior of the 

 neck and bulb of the sac there is distinctly seen a tube which is 

 narrow below, but somewhat dilated at the part corresponding to 

 the bulb of the sac. This tube I have observed in several in- 

 stances prolonged upwards, passing out at the terminal fissure 

 and ending in a papilla closed at the extremity. I have traced 

 it some way into the interior of the body of the sac, but the pre- 

 sence of the cellular contents has prevented me from being able 

 clearly to see its relation to the very minute embryo, whose out- 

 line might be seen shining through. In one preparation in my 

 possession there is an appearance which seems to indicate a con- 

 nexion between the embryo and the tube, but I cannot decidedly 

 assert that they are continuous. Lying parallel to the embryo- 

 sac, and on the side next the short podosperm, there is another 

 organ similar in structure ; it may be compared to a Florence flask 

 in shape ; the necks of the two are quite continuous. 



The nature of this remarkable appendage was not easily com- 

 prehended at first. I am inclined to believe that the arrange- 

 ment of the parts in Euphrasia is somewhat similar to that in 

 some species of Veronica, and which has been described and 

 illustrated by M. Planchon, to the accuracy of whose descrip- 

 tions and delineations I can bear testimony from my own observa- 

 tions. In the earlier stages of the ovule in Veronica the upper 

 end of the sac is bulbous, below this it tapers into a neck, then 

 becomes again somewhat dilated at the part in which the embryo 

 afterwards appears, and which may be called the body of the sac ; 

 towards the posterior end it gradually becomes narrower and 

 < luls in a sharp point. At more advanced stages the neck of the 

 >ac ])resents several varicose appendages. The large appendage 

 already described as lying parallel to the embryo-sac in Euphrasia, 



