EXTRACTS AND ABSTRACTS FROM FOREIGN JOURNALS. 183 



When the caulinear spongioles are developed on a stem, its preserva- 

 tion in pure water may be relied on for an indefinite length of time ; 

 but its growth is none or inappreciable, for these are not the normal 

 organs of absorption. It is not the same even with the absorption 

 which operates by means of the development of special organs, at first 

 confounded with lenticels, but which, according to the observations of 

 M. Bouchardat, are essentially distinct. Considering these latter organs 

 as the true root-buds, he has given them the name of Rhyzogenes. 



" At first," says he, " the Rhyzogenes and Lenticels might be con- 

 founded ; nevertheless a little attention will render evident the fact that 

 whilst the latter are distributed without order on the bark, the others 

 have a regular mode of distribution. Further, lenticels are flat, or 

 very slightly swollen ; rhyzogenes, on the contrary form conical protu- 

 berances ; lastly, microscopical examination shows, that whilst the len- 

 ticels are as before stated essentially composed of cellular tissue, and 

 solely in connection with the external part of the bark rhyzogenes are 

 formed of a number of vessels and cellular tissues and have an evident 

 communication with the woody axis. The preservation of the green 

 parts of a branch may be the result of a simple development of the 

 caulinear spongioles, as above stated; but it is only by the growth of 

 rhyzogenes that a true increase of structure can take place." 



The portions of the lower part of the stem at the point where the 

 rhyzogenes are developed, have given rise to true roots, modified accor- 

 ding to a particular manner, and the study of the changes presented, 

 appears to M. Bouchardat, to be able to furnish a new argument in 

 favour of the theory of M. Du Petit Thouars, on the mode of growth 

 of plants. 



For the Science of Botany properly speaking, the consideration of 

 rhyzogenes, has also according to the author, a certain importance, and 

 may be able to furnish good characters for distinguishing one from the 

 other in nearly allied species. 21st of June, 1841, p. 1172. 



[From Valentin's Repertorium, 1841.] 



Valentin on Parasites in the Bladder of the Frog. In spring and sum- 

 mer I found a great number of parasitical animals within the urinary 

 bladder of the frog, which probably represented transitional conditions 

 between the Infusorial-like creatures and Distoma cygnoides observed 

 by MIESCHER in the same viscus. At their anterior extremity they pos- 

 sessed a large excavation, becoming narrower posteriorly, at the bottom 

 of which was an opening, having two distinct marginal lines, and sur- 

 rounded by radiating folds. Behind this, on the external surface of the 

 body, was a wreath of cilia, which in the live animal was in active mo- 

 tion, but in the dying creature moved but slightly, and in a pulsating or 

 rythmical manner. By means of these organs the parasite moved itself in 

 a circle, without exerting any great locomotive action. Through the 

 opening at the bottom of the discoid excavation, a smaller, though yet a 

 comparatively large and round body might be observed, which, when 



