154 W. H. LONGLEY 



is formulated. Such a conception is to be attained bj' the study 

 of tube eggs before fertilization or during the earliest stages of 

 that process. These are chosen, first, because, they are proven 

 by their condition to be normal, for they are the eggs which pro- 

 duce the new generation, and second, because they must retain 

 most completely the characters of the mature ovarian egg. For 

 an example of such an egg see figures 11 and 12. 



Such tube eggs are approximately spheres. Each possesses 

 a zona pellucida of considerable and nearly uniform thickness, 

 within which there are no leucocytes or granulosa cells. The 

 corona surrounding each has its radiating structure developed 

 to the extreme. Therefore when ovarian eggs are found pos- 

 sessing the characters indicated they are to be considered nor- 

 mal. The follicles containing such eggs, moreover, exhibit a 

 common set of characters which are serviceable in defining the 

 class of eggs which is approaching maturity in full possession of 

 its capacities for development. 



The normal follicle, (fig. 3), just before its rupture, is provided 

 with a thin granulosa layer usually onl}" two to four cells thick, 

 except in the region of the cumulus. The egg in it contains a 

 second polar spindle, and is accompanied by a first polar body. 

 It lies practically free in the follicle, surrounded by its zona and 

 corona. Nevertheless it is perfectly plain that the thickness of 

 the granulosa cells in the preceding stage was not uniform, but 

 that they were aggregated to form a prominent cumulus jutting 

 well out into the antrum. There are always many layers of cells 

 between the egg and the membrana propria, although there is 

 evidence of lacunae between the cells of the cumulus. 



The normal ovarian egg nearing maturity must then be approx- 

 imately spherical, must have a thick zona with no foreign cells 

 within it, must not have had its corona affected in such a way that 

 its power of assuming the highly developed radiate structure is 

 lost, and finally must be in a follicle with a high cumulus, with 

 many layers of cells between it and the basement membrane. 



With these facts in mind, it is impossible to consider those eggs 

 normal which are found undergoing maturation in the ovaries 



