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heat, also a fair supply of moisture, at least in the growing season, say a 
mean annual temperature of 59°-68° Fahr., that of the rather warm tem- 
perate zones. The fourth group, Microthermal plants, i.e., those demanding 
little heat, say a mean annual temperature of 57° or less, down to that of 
32°, with of course a good summer temperature. In this group would he 
included the vegetation of our Northern States and Canada. The fifth 
group, Hekistothermal plants, those requiring least heat, such as make up 
arctic, antarctic, and alpine vegetation. His sixth group, Megistothermal 
plants, those which require an exceptional amount of heat, or a mean of over 
86° Fahr., are mentioned as having probably played a part among the earlier 
vegetations, but as now represented only by a few lowly organized plants of 
thermal waters. He then goes on at a great length to consider the subject 
more fully, but of course we have not space here to follow him. 
Wild Flowers and their, relations to Insects. — This subject was admirably 
handled in the able lecture delivered on one of the evenings of the British 
Association, at Belfast, by Sir J ohn Lubbock. In this, which we regret we 
have not space to lay before our readers, the author entered upon a summary 
of all that is known on the subject at present, and gave several of the 
results arrived at by Darwin and himself. The address we trust he will 
publish in full, with the illustrations, for assuredly it is one of the most in- 
structive and interesting subjects in the whole range of science. 
A Sketch of Systematic Botany. — At the British Association Meeting at 
Belfast, Mr. G. Bentham, F.R.S., read a paper on “The Decent Progress and 
Present State of Systematic Botany,” commencing with a summary sketch 
of the state of the science in 1830, when the natural method of Jussieu was 
beginning to supersede the sexual system of Linnaeus ; of its progress from 
that year to 1859, when the study of the general affinity of plants had 
entirely superseded the classing them according to single organs; and of the 
great advance effected since 1859 owing to the explanation of affinities 
given by the adoption of the doctrine of evolution. After some notes on 
the language to be preferred, systematic works were considered under the 
six general heads of ordines plantorum, genera plantorum, species plantorum, 
monographs, floras, and miscellaneous descriptions. Under each head the 
particulars required were specified, the principal recent works glanced over, 
together with a short mention of the chief desiderata now recommended to 
the attention of systematic botanists. 
Fmbryogeny of Tropceolum. — Professor Dickson gave, at the British 
Association at Belfast, the results of his investigations on the embryogeny 
of Tropceolum peregrinum and Tropceolum speciosum. In these species the 
principal peculiarity consists in the constant penetration of the carpellary 
tissue by the extra-seminal root process. In Tropceolum majus the extra- 
seminal root process developed from the outer side of the base of the 
suspensor. After perforating the seed-coat becomes elongated, and finishes 
its course in the cavity of the seed-vessel. In rare cases, however, this 
process has been found to penetrate by its very extremity the carpellary 
tissue. In Tropceolum peregrinum the extra seminal process penetrates the 
carpel after having run in the cavity of the seed-vessel half way. In 
Tropceolum speciosum this process dips into the carpel immediately after 
emerging from the seed. Dr. Dickson remarked that some would be dis- 
