326 Canadian Record of Science. 



sites of mucous glands, which Prof. Lankester mentions as 

 a feature of shields of the genus Pteraspis: from this he 

 infers that a secreting membrane probably covered the sur- 

 face of the calcareous plates in Pteraspis. If his reasoning 

 is correct, the plates of the Acadian fish were also probably 

 clothed with a similar covering. 

 St. John, KB., Dec, 1886. 



Miscellaneous. 



Radiation from Plants. — Acting upon the suggestions contained 

 in Darwin's well-known experiments relative to the protection 

 against excessive radiation from leaf surfaces, and so against injury, 

 afforded by the various positions which certain leaves are known to 

 regularly assume at night, Rev. G. Henslow seeks a more general 

 application of the law than had previously been observed. He finds 

 that even in those plants, the leaves of which are not so hypnotic in 

 the mature state, there is usually well-defined hypnotism in the 

 young leaves, and that in any case, the vernation bears a most 

 important relation to the protection of leaves against radiation from 

 their uppsr surfaces, and also against dessication through the action 

 of dry winds passing ever them. In the latter case, he shows by 

 experimental determination, that in many cases, the loss of moisture 

 in weight, from young leaves artificially extended, exceeds that 

 from leaves which maintain their normal form of vernation, several 

 times. Of the examples which he cites, the ratios of loss between 

 the naturally and artificially exposed leaves, vary from 1 : 5"1 to 

 1 : l - 2. — Jour. Lin. Soc, xxi. 



Development in Septic Organisms. — The Rev. W. H. Dallinger, 

 in his presidential address to the Royal Microscopical Society, 

 in February, 1866, traced in a masterly manner the development 

 of certain forms found in septic fluids, requiring for their study 

 at once the very best instruments and the greatest skill. This 

 unrivalled investigator modestly left out of account the skill, and 

 dwelt on the great improvements in microscopes within the last 

 few years. An outline of what takes place cannot better be 

 sketched than in Dallinger's own words. The creature (monad) 

 he describes as a protoplasmic cell with nucleus, and having a 

 pair of flagella projecting from the pointed end. " The nucleus is 

 the centre of all the higher activities of these organisms. The 

 germ itself appears but an undeveloped nucleus ; and when that 

 nucleus has attained its full dimensions in size, there is a pause 



