ATMOSPHERIC MICROGRAPHY. 165 



as little can I share the opinion of Kowalevsky, who declares 

 the invaginated cavity or segmentation cavity to be the first 

 trace of the body-cavity. I can only perceive in the hollow 

 which is formed during the grooving between the furrowed 

 cells, and which afterwards forms the hollow of the germinal 

 vesicle (vesicula blastodermica), a casual hollow without 

 any permanent morphological signification. It, indeed, always 

 disappears again in the course of ontogenesis, and never passes 

 directly into the true coelom. This last makes its first 

 appearance much later, as a really new formation, a division 

 between the two muscular layers. According to Kowalevsky's 

 view, the coelom would be phylogenetically much older than 

 the intestinal cavity, w^hereas the reverse is actually the case. 

 The intestine has certainly existed very long as a primitive 

 organ in the Zoophyta and Acoelomi, before it developed (in 

 the Coelomati) the true body-cavity between the intestinal 

 wall and body-wall. 



{To be continued.) 



Atmospheric Micrography, by the Rev. M. J. 

 Berkeley, M.A., F.L.S. 



Since Ehrenberg's remarkable treatise on the ' Dust of the 

 Trade Winds,' numerous observations have been made on the 

 various substances which float in the atmosphere, either in 

 connection Avith their supposed influence in the production or 

 promotion of disease, or with reference to the great contro- 

 versy respecting spontaneous generation. These observations 

 were, however, frequently made in utter ignorance of the 

 true nature of the organisms in question, or with strong pre- 

 judices in favour of some particular theory, in aid of which 

 they were interpreted. It became part of the duties of Dr. 

 Cunningham and Dr. Lewis, who were sent to India by our 

 Government to investigate thoroughly everything which 

 might throw light on the origin of cholera and other for- 

 midable diseases to which our Eastern possessions are 

 especially subject, and from which one of the most formidable 

 in other countries certainly originated, amongst other mat- 

 ters, to see what was really carried about by the winds, and 

 the results of the inquiry which more peculiarly fell to the 

 share of Dr. Cunningham are certainly most extraordinary. 



regarded the coelenteric system of cavities in the Zoopbjta as au iatestiuul 

 cavity. 



