3/6 Mr. Hogg's Observafimis on the Spongilla fluviatilis, 



rules, and as they ace so extremely similar to those of certain species of the 

 Marine Sponge, which were discovered in 1825 by Dr. Grant, I could not 

 help thinking that in spite of the strong evidences which I had indisputably 

 obtained in favour of its vegetable nature, I had also discovered one, which 

 would perhaps go far in proof of its animality, and thus compel me to be- 

 come somewhat of an unwilling believer in the monstrous theory which lias 

 of late years been revived amongst some foreign naturalists*, that certain 

 bodies belonging to several Cryptogamous plants are at first animals, and 

 that after a time they change into true vegetablesf. Notwithstanding the 

 power of locomotion has generally been accounted as one of the strongest 

 tests of animal life, and that which constitutes the most obvious difference 

 between an animal and a plant, still this power is not alone confined to the 

 beings included in the first great division of nature ; for many observers have 

 witnessed it in subjects which pertain to, and really are members of the se- 

 cond division, or the vegetable kingdom. I here allude to the extraordinary 

 phenomena, which have been noticed by some distinguished botanists on the 

 Continent, as to the locomotive powers of the seeds or sporules of certain 

 Confervœ, as well as of other plants belonging to the Algœ ; and more espe- 

 cially to the singular discoveries of Dr. Unger in 1826, which relate to the 

 spontaneous movements of the seeds of the Ectospenna clavata of Vaucher;}:. 

 The original memoir descriptive of these appearances is contained in the Act. 

 Acad. Nat. Curios, vol. xiii. p. 791. Bonn, 1826, with an accompanying plate. 



* As far as I can find, Munchausen was the first author of tliis theory nearlj- half a century aeo, 

 but he seems to have obtained few followers until very recently. For further opinions on this theory 

 refer to Nématophytes, p. 524, vol. Ix. of the Dictionnaire des Sciences Naturelles, edit. 1830 : likewise 

 the articles Némazoaires and Kémazoones. at p. 365, vol. sxxiv. of the same Dictionnaire ; and the ar- 

 ticle Psychodiaires, p. 516 of vol. xliii. of the same work. 



t This theory may be termed the Zoocarpical, or that relating to imaginary animal-seeds. Dr. Roget 

 writes, "The tribe of Zoocarpia" (certain of the Cryptogamia I suppose) " produce a kind of fruit 

 (seed), which when detached from the parent, appears to possess powers of spontaneous motion until 

 the period of its taking root, and growing like a vegetable structure." Note, p. 156. vol. i. Roget's 

 Bridgewater Treatise. But according to M. Bory de Saint-Vincent, with whom the name originated, 

 " 'les Zoocarpes' sont les séminules animés, des véritables végétaux ;" /. e. the live or animate seeds of 

 certain true plants. 



J This plant is s}Tionymous with the Vaucheria clavata of DeCandoUe ; and the Conferva dUutatu 

 i3. clavata of Roth, and y. bursata are only different states of the same. 



