Embryology, with the physiology of generation ... / Translated from the German, with notes, by William Baly ... From Müller's Elements of physiology and supplement.
- Johannes Peter Müller
- Date:
- 1848
Licence: Public Domain Mark
Credit: Embryology, with the physiology of generation ... / Translated from the German, with notes, by William Baly ... From Müller's Elements of physiology and supplement. Source: Wellcome Collection.
43/376 page 1443
![cates with the canal of the stem. Subsequently the organisation of the polype takes place, and then the extremity of the gemma opens and the arms of the polype are put forth.* The formation of gemmae is very frequent amongst the Polypifera, but less so amongst the In¬ fusoria. Spallanzani and Ehrenberg have observed it in. the Vorticellinse (see fig. 151). Perhaps the naides should be regarded as multiplying by the formation of buds. For since the young individuals are formed from the hinder part of the parent animal (see fig. 145, p. 1425), and since at this part new segments are constantly being formed, it is possible that the young organisms which separate from the parent body are merely gemmae which have undergone develop¬ ment, and consequently that the apparent spontaneous division of the parent body is really a throwing off of terminal buds de¬ veloped upon the parent stem. The compound polypiferous animals in¬ crease by the production of gemmae, which do not separate from the parent stock, and thus give rise to a constantly extending mass, which includes successive generations of united indi¬ viduals. In many animals,—as the Ascidite, Xeninae, Sertularinae, and Alcyonellae, the gemmae are formed upon stoles or running stems.J We have seen that in plants, after the terminal and lateral branches are cut away, the stem will produce buds. A similar fact is observed with respect to the polypifera: sometimes, when all the individual polypes have perished, the formation of buds upon the stem will continue. Fig. 151. *j* A £ CHAPTER IV. OF THE SEPARATION OF THE BUDS OR GEMMA, OR OF THE DIVISION BETWEEN THE STEM AND BUD. Buds may separate spontaneously or be detached artificially, so as to become perfectly independent individuals, either in their simple state or when they have already by development acquired the organisation * Lister, in Philos. Transact. 1834, Pt. ii. [Also Farre, Philos. Transact. 1837.] -j* [Vorticella microstoma multiplying by gemmation. A and B show successive stages in the development and separation of the young animal. 1, mouth ; 2, con¬ tractile sac ; 3, sexual gland ; 4, stomach • 5, ova. After Ehrenberg, Infusions- thierchen, t. xxv.] J See Ehrenberg, in Bericht uber die Verhandl. der Akad. der Wissensch. Zu Berlin, 1836.](https://iiif.wellcomecollection.org/image/b29339601_0043.jp2/full/800%2C/0/default.jpg)
