84 Translation from Purkinje 



(7) This is the fluid of the subgerminal cavity which had been of great importance since 

 Aristotle in the discussions of the interchange between the "moist" albumen and the "earthy" 

 yolk (see Fabricius in translation of Adelmann,^ p. 176 ss.). 



(8) The fact that a hen may lay fertile eggs for weeks after isolation from the cock was 

 known to Aristotle and was responsible for much of the mysticism surrounding the process of 

 fertilization. William Harvey believed that the "aura seminaUs" fertilized the clutch of eggs in 

 the ovary. This idea is not compatible with Aristotle's statement that if a hen is mated and 

 subsequently trodden by a second cock "while the eggs are still yellow," that is, still in the 

 ovary, the chicks will resemble the second cock. It is quite possible for part of a clutch to 

 be fertilized by one cock, the rest by another. (See Fabricius in Adelmann,^ pp. 191 ss.). 

 Intraovarian fertilization was actually advocated in 1924 by Iwanow (see Hartman*"). The 

 problem of where the spermatozoa remain during this period of great oviducal activity has 

 yet to be solved, but the suggestion of intraovarian fertilization at the present time indicates 

 only ignorance of the histology of the avian ovary and the early history of the bird's egg. 



(9) The pigeon's egg is over a millimeter greater in diameter after ovulation than the entire 

 follicle was before rupture. This would indicate a rapid resorption of fluid by the yolk at this 

 time and during the condensation of the chalaziferous albumen (Bartelmez,^^ p. 293). There is 

 considerable fluid in the abdominal cavity at the time of ovulation; see §10 of the text. 



(10) The original in both editions reads: "alba haec vitelli substantia in enixis primum ovis 

 luculentissime observatur." 



I owe to Dr. Adelmann the interpretation of "primum" indicated in the translation, 

 namely, that Purkinje advises anyone who looks for the latebra for the first time to begin 

 with the readily available laid eggs. As a matter of fact the boundaries of the latebra are 

 clearest in large ovarian oocytes and they rapidly become hazier with incubation. It is pos- 

 sible that Purkinje intended "primum" to signify "newly" laid eggs. 



(ii) This footnote sounds a bit as if Purkinje had his tongue in his cheek as he replied to a 

 criticism that he had not adequately considered the older literature after the manner of 

 "scholars" who had nothing to write about except what they had read in books. 



Bellini developed the notion that the primordium of the chick, which he identified with 

 the cicatricula and with the "sacculus amjiii" as well, must be kept away from the air space 

 imtil incubation had begun, otherwise there would be a great accumulation of gas as in 

 the rotten egg! ("Digressio de ovo," "Ovi aere," etc., in his De Motu Cordis,*^ 1693). He be- 

 lieved that the cicatricula passes from the surface into the "viscera" of the yolk on boil- 

 ing as the result of the evaporation of a "liquidum tenuissimum" from the "central cavity." 



(12) The original reads: "De Baer ... nostram de latebra centrali vitelli ad theoriam de 

 halonibus applicavit." The translation implies that Purkinje was punning and using the 

 original meaning of Oeuipia (a viewing) for his own observations in contrast to the derived 

 meaning, namely, "theory," for von Baer's application. This theory may be found on 

 p. 10 in Vol. I of von Baer's Entwickelungsgeschichte .^ 



(13) Concentric bands in the yolk were described by William Harvey. Riddle"" in 191 1 was 

 the first to explain the differences betAveen the alternate strata of white and yellow yolk. 



(14) There is, however, a period in the early growth of the ovarian egg (oocytes from 0.3 

 to 1.0 mm. in diameter) when the germinal vesicle is not peripheral, although it is always 

 eccentric, so that the polar axis remains obvious (Bartelmez**). 



(15) This matter was not again carefully studied until 1910 by Maynie R. Curtis" (see 

 translator's note 16). 



(16) Phillips and Warren"^ have described the process of ovulation in detail. Certain find- 

 ings eliminate oviducal activities as factors in ovulation. Thus it may occur in the absence 

 of the oviduct (Pearl and Curtis),^ or after the petiole has been tied off and the entire 

 follicle has been cut from the ovary and left free in the body cavity (Phillips and Warren^-). 

 This may represent an altered permeability of the vitelline membrane and the taking up of 

 water from the fluid which is abundant in the coelom at this time (see translator's note 9). 



