162 Profeesor Ehrenberg on the Microscopic Aniinala 



bigny, Nilsson, Piisch, and other distinguished geological and 

 zoological obsei'vei's, since the year 1826, have noticed indivi- 

 dual larger forms of polythalamic nautili in the chalk of 

 France, Sweden, and the Bidcowina ; although the author him- 

 self (in 1836) proved to the Academy the existence of many 

 calcareous polythalamia^ in the flints of the chalk, which en- 

 abled us to infer the presence of prodigious multitudes of such 

 bodies in chalk ; and although, in the tabular view printed in 

 1837, he named these Hotalites ornatus {Lenticulina, Londs- 

 dale), and Textularia glohulosa (^Discorbis, Londs.), as the 

 chief forms of the Folythalamixe, and Cypris Faba ? {Cytha- 

 rina, Londs.), as an Entomostracon of the chalk; although, 

 moreover, Mr Londsdale, of London, lately (in 1837) reckoned, 

 with the naked eye, 1000 white granules in a pound of English 

 chalk ; yet the numbers and masses of forms, chiefly invisible 

 to the naked eye, which the author of the present paper has 

 very recently observed, though anticipated by him, are very 

 much greater. In these investigations he employed a new 

 and peculiar mode of observation. 



As limestone and chalk, by being mixed with water, and 

 magnified 300 times, are seen to contain, besides the granular- 

 foliated particles, likewise coarser opaque particles, which at 

 first seemed to be mere dark parcels of these elliptical gra- 

 nules, or small fragments of larger organisms, the author tried 

 several oils and balsams that increase transparency. These 

 had previously been employed by the aiithor with advantage 

 and success, in the case of infusory animals ; but there they 

 were less useful, as they increased the transparency to such an 

 extent as to destroy all light and shade, and also the outlines. 

 But such experiments Avere eminently successful with the cre- 

 taceous animalcules, more especially when turpentine was em- 

 ployed ; and of this, the best kind is that obtained from the 

 Finns balsamea, and which is known in the shops by the name 

 of Canada balsam. The use of this substance on finely divided 

 dry chalk, particularly after heat had been applied, distinctly 

 afforded to the author a result which had previously been ob- 

 scure, viz. that the said chalk contains so vast a multitude of 

 microscopic, and hitherto unknown polythalamiae, or nautilites, 

 as they have been termed, having a size of from l-24th to 



