138 CONTRIBUTIONS TO VEGETABLE EMBRYOLOGY. 



This small number contains two new species, and the Rotalia of the 

 chalk, the lower shell of which is here abundant, indicates the marine 

 or brackish origin of these animalculse. Moreover the occurrence here 

 of Tetragramma Libycum, is remarkable, as being a form which a short 

 time since was met with in saliferous earth brought from Siwa, in the 

 Oasis of Jupiter Ammon, and at one time was found nowhere else. 



As a general result of these researches, the following may be pro- 

 posed : 



1 . There are in Iceland as in North America, useful beds of good 

 peat, consisting, in great part, even to as much as the of their bulk, 

 besides vegetable remains, of dead microscopic animalcules whilst the 

 most common European good kinds of peat, although Infusoria when 

 sought for are rarely found wanting in them, have not hitherto been 

 found to contain them in the same proportion. 



2. There is a minute organic invisible life diffused entirely through 

 those parts of the soil rich in humus ; but sandy situations of the 

 earth's surface from near the South to the neighbourhood of the North 

 Poles, and the bottom of the sea near the North Pole, are also filled 

 with similar organic forms. 



3. It is possible according to the method of research pursued by the 

 author, to render evident the forms in which this life occurs, from the 

 smallest particles of earth adhering to the plants in Herbaria, or to 

 bodies of any kind ; and to determine much further than has yet been 

 done, with ease and scientific certainty, a more or less numerous fauna 

 of microscopic organisms, from all parts of the earth. 



XXIV. CONTRIBUTIONS TO VEGETABLE EMBRYOLOGY, FROM OBSER- 

 VATIONS ON THE ORIGIN AND DEVELOPMENT OF THE EMBRYO IN 

 TROP.EOLUM MAJUS.* 



By Herbert Giraud, M.D. 



AFTER referring to the researches of MM. Schleiden, Wydler, Mirbel 

 and Spach, and A. St. Hilaire, on this important point, Dr. Giraud 

 states that he was induced to select Tropceolum as the subject of his 

 own observations on account of its solitary ovula, and their compara- 



* Abstract of a Paper read before the Linneean Society, February 1st, 1842, and 

 published in the Proceedings of that body. 



