OVUM. 



[HI] 



Fig. 75*. 



tained by that author, were extended over a 

 very large number of Insects. Among nearly a 

 thousand different kinds, he succeeded in de- 

 tecting the existence of the micropyle in not 

 less than two hundred ; and his detailed ob- 

 servations on this apparatus, and the structure 

 of the membranes, extend to one hundred and 



Fig. 76*. 



Micropyle in the ovum of Insects. (From Meissner.') 



a. A portion of the upper pole of the ovum of 

 Musca vomitoria from the Vagina. There are 

 shown in succession the vitelline membrane, chorion 

 and outer envelope, and at the upper part in profile 

 the micropyle aperture situated in the middle of a 

 nipple-like projection of the chorion, and with a 

 number of spermatozoa involved in it. 



b. Direct view of the upper pole of the ovum of 

 an insect belonging to the Pyralida. The micro- 

 pyle aperture is seen in the centre of the radiated 

 markings of the chorion. 



micropyle apparatus in the ova of Insects be- 

 longing to the following genera, viz., Musca, 

 Tipula, Culex, Lampyris, Elater, Teleopho- 

 rus, Adela, Pyralida, Tortrix, Euprepia, Li- 

 paris, Pieris, Panorpa, and in more than one 

 species of several of these genera. The same 

 author also observed and described in Musca 

 vomitoria a number of spermatic filaments 

 entangled in the micropyle. 



Leuckart's observations, which are fuller 

 and more minute than those of Meissner, and 

 differ in some of their results from those ob- 



&c., of the Ova of Insects, chiefly pupiparous, in 

 Miiller's Archiv. Xos. 1. 2. and 3., February and 

 July, 1855, p. 90., ft seq., with five plates, with 122 

 figures. There can be no doubt that both of these 

 authors made the independent discovery of this 

 curious structure. Perhaps the priority claimed by 

 Leuckart, may be accorded to him, as he had pre- 

 viously stated the probability of its existence in his 

 article " Zeugung," published in 1852, p. 906. 



Micropyle of the ovum of Lepidoptera. 

 Leuckart.) 



(From 



A. Side view of the upper part of the ovum o 

 Sphinx Populi, showing the micropyle, the radiated 

 markings surrounding it, and the cellular and other 

 structure of the coverings of the ovum. 



B. More enlarged and direct view of the vicinity 

 of the micropyle in the same. The dotted or punc- 

 tated structure belonging to the chorion is here re- 

 presented. 



eighty species. This must furnish ample 

 proof of the universality of the existence of 

 the micropyle in this class of animals, when 

 we consider the minuteness of the object and 

 the difficulty of obtaining specimens in a con- 

 dition suitable for the investigation. Leuckart 

 has stated, indeed, that in all instances in which 

 the ova were ripe and favourable for examina- 

 tion, he was enabled to assure himself of the 

 presence of this apparatus. 



In a certain number of instances, amounting 

 to about a dozen, Leuckart farther found that 

 the spermatozoa adhere to the micropyle, and 

 that a certain number of them pass into the 

 ovum by this aperture. He observed that a 



