Dr Martin Barry's Researches in Emhryology. 43 



I cannot refrain from here repeating that he who, in re- 

 searches on the mammiferous ovum, does not very minutely, 

 and very patiently, and again and again, examine ova during 

 that period, i.e., in the ovary post eo'itum, is quite incapable 

 of understanding them in the uterus or Fallopian tube. 



Another cause of ignorance that recent works by a German 

 author shew still to exist regarding the mammiferous ovum 

 in the Fallopian tube and uterus, is its perishable nature. 

 This inconvenience is felt chiefly in examining ova the essen- 

 tial part of which has left the centre and reached one side ; 

 for the chances are against that side being directed towards 

 the eye. You cannot turn the ovum round and round with- 

 out destroying it, for to a body so delicate it is impossible, 

 even with the finest hair pencil, to apply an equally delicate 

 manipulation. And supposing you at length find one having 

 the essential part directed upwards, a few minutes will not 

 suffice for the examination, of which some figures that have 

 been published afford ample proof. Some medium is required 

 in which the examination maybe more perfectly accomplished. 

 The smallest ova from the Fallopian tube and uterus it was 

 my practice to view imbedded in some of the mucus taken from 

 those parts, after I had excluded the air in a manner formerly 

 described.* For any but the smallest a transparent fluid is 

 required. I tried a large number, and all were found unsuit- 

 able excepting one. That one was a saturated aqueous solu- 

 tion of Kreosote, which I still most particularly recommend 

 as a medium in which the ovum may be examined day after 

 day, and may be even delineated at the end of several days.f 



Besides the facts and conclusions already referred to in 

 this communication, my papers on Embryology will be found 

 to contain others, among which are the following, viz. : — 



8. The existence and mode of origin of a vesicle not pre- 

 viously described, which I shewed to be common to the ova 

 of vertebrated animals, and to constitute the foundation of 

 the Graafian follicle, a vesicle which I followed upwards from 



* Phil. Trans. 1839, Part ii., pp. 365, 367. 



t Phil. Trans. 1839, Tart ii., p. 3A5, Plate 8, fig. 138, a drawing taken 

 after the ovum had lain in Kreosote water for three days. 



