APPENDIX. 789 



mation of a corpus luteum. How is this ? The explanation which might 

 be offered of such rare cases is this : Coitus may have chanced to take 

 place at the very time when a Graafian follicle, having become mature, 

 had spontaneously given way and expelled the ovum. No congestion, 

 exudation, and extravasation, would in this case take place, but the part 

 would quickly close and cicatrize. 4. Lastly, what explanation can be 

 given of the origin of false corpora lutea ? To this it might be answered, 

 that from some circumstance or other, effusion of blood takes place into 

 the interior of a Graafian follicle, perhaps on the point of bursting 

 spontaneously. This blood coagulates and remains filling and distend- 

 ing the Graafian follicle, even although its walls may have subsequently 

 given way. But besides this effusion of blood, an exudation of lymph 

 takes place on the inner surface of the walls of the Graafian follicle, in 

 consequence of the irritation produced, which, becoming organized, pre- 

 sents the same yellow appearance as the substance of the true corpus 

 luteum formed outside the walls of the Graafian follicle. 



" In conclusion, I would remark that, though physiologically one may 

 be permitted to speculate, as I have done, on the relation between the 

 occurrence of corpora lutea in the ovaries and preceding coitus, it would 

 be rash and unwarrantable in any one to pronounce positively from the 

 occurrence of a corpus luteum in the ovaries that coitus had taken place. 

 The discovery of an ovum > in the uterus, in process of development, 

 could alone, in the present state of knowledge, warrant such an affirma- 

 tion in a court of law. But, on the other hand, the absence of a corpus 

 luteum could not warrant the affirmation that coitus had not taken place." 



4. Development of the Teeth. In an Essay on this subject in the 

 " Quarterly Journal of Microscopical Science," for April, 1853, we have 

 taken a very different view from that advocated by Professor Kolliker, 

 and which amounts to this, that all the tunics of the teeth are the result 

 of calcareous deposition from the pulp, the so-called " enamel organ" 

 taking no direct share whatever in the process. This view was based 

 upon observations made upon the teeth of all the principal orders of the 

 Vertebrata, i. e., the Mackerel, the Skate, the Frog, the Calf, and Man; 

 and subsequent observations on these and on other animals, have only 

 confirmed our belief in the substantial truth of the matters of fact there 

 stated. 



The keystone of the theory of dental development there enunciated 

 is the fact, that, in all the orders of the Vertebrata, a membrane homo- 

 logous with the so-called "persistent capsule," discovered, in 1839, by 

 Mr. Nasmyth, and which we have therefore denominated " Nasmyth's 

 membrane" can be demonstrated covering the enamel of the teeth and 

 extending over the dentine, to be continuous with the membrana prefor- 

 mativa and basement membrane of the sac, in an incompletely formed 



