390 BULLETIN OF THE 



But among those who have insisted on the derivation of the polar 

 globules from the germinative vesicle, there has been considerable diver- 

 sity of opinion. As we have just seen, Dumortier held the globules to 

 be the vesicle itself. Van Beneden and Windischmann inclined, as pre- 

 viously stated (p. 236), to the same opinion. 



Loven ('48, pp. 535-539), on the other hand, expressed, with some 

 reserve, the opinion, that in lamellibranchs it was the germinative dot 

 which, after rupture of the vesicle, became expelled. Leydig {'49, 

 p. 125) conjectured the same to be true for Piscicola, and Bischoff ('42, 

 pp. 54, 146) held to the idea that the globules observed by him in the 

 rabbit were at least derived from the germinative dot. 



More recently Flemming ('74, pp. 278, 279) has niaintained that it is 

 neither vesicle nor dot, but a product of the metamorphosis of both, 



and believed them to he the Purkinjean vesicle. They were observed in the case of 

 Aplysia by P. J. van Beneden ('40, pp. 242, 243, 245) who called them "vesicules 

 blanches," and in the same paper mentions their occurrence in Limax, although the 

 first account of their formation in Limax was that given by Van Beneden and Win- 

 dischmann ('41, pp. 20, 21) in the year following. 



Fr. Miiller ('48, p. 3) attributed to these bodies an importance in determining the 

 position of the planes of segmentation, and hence gave them the current German 

 name "Richtungsblaschen." 



Robin ('62*, ]). 150), also recognizing their constant relation to the early segmen- 

 tation planes, calls them "globules polaire," but believes tliat they are derived, not 

 from the germinative vesicle or germinative dot, but from an accumulation of clear 

 yolk at one pole of the egg, and that granular portions of the yolk may secondarily 

 make their way into the globules while the latter are in process of formation. Sev- 

 eral observers have alluded to the name polar globules as though it were first used by 

 (the elder ?) Van Beneden. I have not succeeded in finding the use of that expression 

 in the earlier writings of P. J. van Beneden, and am therefore of the opinion that 

 Robin was the first to make use of this term. 



P. S. — Fol ('79, p. 146 or p. 58 of separate) casts doubt on the nature of the ob- 

 servations made by Carus and Dumortier. He says they are currently, in his opinion 

 wrongly, believed to have discovered the polar globules. " It has been impossible 

 for me," he adds, "to find in the works of these authors the description of coipuscles 

 which are referable with probability to the polar globules." 



I have likewise been unable to find any description in Carus referable to polar glob- 

 ules, unless the allusion {loc. cit., p. 53) to "hellere durchscheinende Stellen (a. h.)" 

 which one distinguishes " an zwei polar entgegengesetzen Punkten " may refer to phe- 

 nomena which in some cases accompany the formation of polar globules ; namely, the 

 accumulation of clear protoplasm at the vegetative as well as animal pole of the (sgg. 

 The protuberance outlined in the figure (IV. A. a.) above referred to represents too 

 closely a nearly completed polar globule to permit assigning any other significa- 

 tion to it, although it may count for little, that, among many projections from the 

 surface of the embryo Carus has chanced to figure, without understanding its mean- 

 ing, one of those sti'uctures over which thei-e has been so much discussion. — With 



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